v7.3.3

Bumps to 7.3.2 the version of `@babel/plugin-transform-typescript` used by `@babel/preset-typescript`.

This allows us to use `@babel/preset-typescript` and pick up at least one useful bug fix (#9095).

A similar PR (#9181) was closed as it bumped to a version that didn't have changes. However reading the comments from that PR, I get the sense that bumping the version in this manner should not be necessary, and should be handled by Lerna. Is this correct?

Please let me know if I can make any improvements to this PR, the description or if there's anything else I can do to help.

.eslintrc.json

@@ -1,7 +1,7 @@
 {
   "root": true,
   "extends": "babel",
-  "plugins": ["local-rules", "prettier"],
+  "plugins": ["prettier", "@babel/development"],
   "rules": {
     "prettier/prettier": "error"
   },
@@ -12,8 +12,8 @@
     {
       "files": ["packages/*/src/**/*.js", "codemods/*/src/**/*.js"],
       "rules": {
-        "local-rules/no-undefined-identifier": "error",
-        "local-rules/no-deprecated-clone": "error"
+        "@babel/development/no-undefined-identifier": "error",
+        "@babel/development/no-deprecated-clone": "error"
       }
     },
     {
@@ -31,7 +31,7 @@
       "files": ["packages/babel-plugin-*/src/index.js"],
       "excludedFiles": ["packages/babel-plugin-transform-regenerator/**/*.js"],
       "rules": {
-        "local-rules/plugin-name": "error"
+        "@babel/development/plugin-name": "error"
       }
     }
   ]

.flowconfig

@@ -1,11 +1,10 @@
 [ignore]
-.*/build/.*
-.*/packages/.*/lib
-.*/packages/.*/test
-.*/codemods/.*/lib
-.*/codemods/.*/test
-.*/node_modules/conventional-changelog-core/
-.*/node_modules/module-deps/
+<PROJECT_ROOT>/build/.*
+<PROJECT_ROOT>/packages/.*/lib
+<PROJECT_ROOT>/packages/.*/test
+<PROJECT_ROOT>/codemods/.*/lib
+<PROJECT_ROOT>/codemods/.*/test
+<PROJECT_ROOT>/node_modules/module-deps/
 
 [include]
 packages/*/src

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -1,6 +1,9 @@
 ---
-name: 🐛 Bug Report
-about: If something isn't working as expected 🤔.
+name: "\U0001F41B Bug Report"
+about: "If something isn't working as expected \U0001F914."
+title: ''
+labels: 'i: bug, i: needs triage'
+assignees: ''
 
 ---
 
@@ -31,7 +34,7 @@ A clear and concise description of what you expected to happen (or code).
 - Babel version(s): [e.g. v6.0.0, v7.0.0-beta.34]
 - Node/npm version: [e.g. Node 8/npm 5]
 - OS: [e.g. OSX 10.13.4, Windows 10]
-- Monorepo [e.g. yes/no/Lerna]
+- Monorepo: [e.g. yes/no/Lerna]
 - How you are using Babel: [e.g. `cli`, `register`, `loader`]
 
 **Possible Solution**

.github/ISSUE_TEMPLATE/Feature_request.md

@@ -1,6 +1,9 @@
 ---
-name: 🚀 Feature Request
-about: I have a suggestion (and may want to implement it 🙂)!
+name: "\U0001F680 Feature Request"
+about: "I have a suggestion (and may want to implement it \U0001F642)!"
+title: ''
+labels: 'i: enhancement, i: needs triage'
+assignees: ''
 
 ---
 

.github/ISSUE_TEMPLATE/Regression-v7.md

@@ -1,12 +1,16 @@
 ---
-name: 💥 v7 Regression
-about: Report an unexpected behavior in v7 from v6 (Check the upgrade guide first ✌️)
+name: "\U0001F4A5 v7 Regression"
+about: Report an unexpected behavior in v7 from v6 (Check the upgrade guide first
+  ✌️)
+title: ''
+labels: 'i: bug, 7.x: regression, i: needs triage'
+assignees: ''
 
 ---
 
 # v7 Regression
 
-> First check out: https://new.babeljs.io/docs/en/next/v7-migration.html
+> First check out: https://babeljs.io/docs/en/v7-migration
 > Also a partial upgrade tool: https://github.com/babel/babel-upgrade
 
 **Potential Commit/PR that introduced the regression**

.github/ISSUE_TEMPLATE/Support_question.md

@@ -1,6 +1,9 @@
 ---
-name: 🤗 Support Question
-about: If you have a question 💬, please check out our Slack or StackOverflow!
+name: "\U0001F917 Support Question"
+about: "If you have a question \U0001F4AC, please check out our Slack or StackOverflow!"
+title: ''
+labels: 'i: question, i: needs triage'
+assignees: ''
 
 ---
 

.github/ISSUE_TEMPLATE/Support_us.md

@@ -1,6 +1,10 @@
 ---
-name: 🤝 Support us on Babel
-about: If you would like to support our efforts in maintaining this community-driven project 🙌!
+name: "\U0001F91D Support us on Babel"
+about: "If you would like to support our efforts in maintaining this community-driven
+  project \U0001F64C!"
+title: ''
+labels: ''
+assignees: ''
 
 ---
 

.github/actions/filter-commit-message/Dockerfile

@@ -0,0 +1,16 @@
+FROM debian:stable-slim
+
+LABEL "name"="filter"
+LABEL "version"="1.1.0"
+
+LABEL "com.github.actions.name"="Filter commit message"
+LABEL "com.github.actions.description"="Stop a workflow if the message of the current commit doesn't match the pattern"
+LABEL "com.github.actions.icon"="filter"
+LABEL "com.github.actions.color"="gray-dark"
+
+ADD entrypoint.sh /action/entrypoint.sh
+
+RUN chmod +x /action/entrypoint.sh
+RUN apt-get update && apt-get install -y --no-install-recommends git
+
+ENTRYPOINT ["/action/entrypoint.sh"]

.github/actions/filter-commit-message/entrypoint.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+set -e
+
+pattern=$1
+message=$(git log --oneline --format=%B -1 $GITHUB_SHA)
+
+if echo "$message" | grep -Pq "$pattern"; then
+  echo "INFO: $message matches $pattern"
+  exit 0
+else
+  echo "INFO: $message does not match $pattern"
+  # 78 is the "neutral" exit status
+  exit 78
+fi

.github/actions/trigger-github-release/Dockerfile

@@ -0,0 +1,18 @@
+FROM node:10
+
+LABEL "name" = "trigger-github-release"
+LABEL "version" = "0.0.1"
+
+LABEL "com.github.actions.name" = "Trigger GitHub release"
+LABEL "com.github.actions.description" = "Trigger a new GitHub release and generate the changelog using lerna-changelog."
+LABEL "com.github.actions.icon" = "tag"
+LABEL "com.github.actions.color" = "yellow"
+
+ADD entrypoint.sh /action/entrypoint.sh
+ADD package.json /action/package.json
+ADD package-lock.json /action/package-lock.json
+ADD release.js /action/release.js
+
+RUN chmod +x /action/entrypoint.sh
+
+ENTRYPOINT ["/action/entrypoint.sh"]

.github/actions/trigger-github-release/entrypoint.sh

@@ -0,0 +1,38 @@
+#!/bin/sh
+
+set -e
+
+echo "INFO: Installing action dependencies..."
+(cd /action; npm ci)
+
+echo "INFO: Checking out current commit..."
+git -c advice.detachedHead=false checkout $GITHUB_SHA
+
+# GitHub doesn't support running actions on new tags yet: we need to run it on the commit.
+# For this reason, we can't be sure that the tag already exists. We can use the commit
+# message to create the tag. If the tag already exists locally, they won't conflict because
+# they have the same name and are on the same commit.
+echo "INFO: Getting release version..."
+# current_tag=$(git describe --abbrev=0 --tags HEAD)
+current_tag=$(git log --oneline --format=%B -1 HEAD)
+
+echo "INFO: Creating new tag..."
+(git tag $current_tag $GITHUB_SHA) || echo "INFO: Tag already exists"
+
+last_tag=$(git describe --abbrev=0 --tags HEAD^)
+echo "INFO: New version is $current_tag; last version is $last_tag."
+
+echo "INFO: Generating the changelog..."
+
+# lerna-changelog expects the token to be provided as GITHUB_AUTH,
+# but GitHub actions don't allow to predefine custom env vars prefixed with
+# GITHUB_. We need to define it here.
+changelog=$(
+  GITHUB_AUTH="$GITHUB_TOKEN" \
+  node /action/node_modules/.bin/lerna-changelog --tag-from $last_tag --tag-to $current_tag
+)
+
+echo "INFO: Publishing the new GitHub release..."
+echo "$changelog" | node /action/release $current_tag
+
+echo "INFO: Done! Don't forget to thank new contributors :)"

.github/actions/trigger-github-release/package.json

@@ -0,0 +1,12 @@
+{
+    "private": true,
+    "name": "@internal/trigger-github-release",
+    "version": "0.0.1",
+    "author": "Nicolò Ribaudo <nicolo.ribaudo@gmail.com>",
+    "license": "MIT",
+    "dependencies": {
+        "@octokit/rest": "^16.3.0",
+        "get-stdin": "^6.0.0",
+        "lerna-changelog": "^0.8.2"
+    }
+}

.github/actions/trigger-github-release/release.js

@@ -0,0 +1,25 @@
+"use strict";
+
+const [ /* node */, /* file */, tag ] = process.argv;
+
+const getStdin = require("get-stdin");
+const octokit = require("@octokit/rest")();
+
+octokit.authenticate({
+  type: "token",
+  token: process.env.GITHUB_TOKEN
+});
+
+const [ repoOwner, repoName ] = process.env.GITHUB_REPOSITORY.split("/");
+
+getStdin()
+  .then(changelog => octokit.repos.createRelease({
+    owner: repoOwner,
+    repo: repoName,
+    tag_name: tag,
+    body: changelog,
+  }))
+  .catch(err => {
+    console.error(err);
+    process.exit(1);
+  });

.github/main.workflow

@@ -0,0 +1,28 @@
+workflow "Release" {
+  on = "push"
+  resolves = ["Trigger GitHub release"]
+}
+
+action "Trigger GitHub release" {
+  uses = "./.github/actions/trigger-github-release/"
+  secrets = ["GITHUB_TOKEN"]
+
+  # When GitHub Actions will support the "release" event for public
+  # repositories, we won't need these checks anymore.
+  needs = [
+    "Is version commit",
+    "On master branch",
+  ]
+}
+
+action "Is version commit" {
+  uses = "./.github/actions/filter-commit-message"
+  # This regex is run using "grep -P".
+  # The (-\\S+) part is for 7.0.0-beta.1 releases.
+  args = "^v(\\d+\\.){2}\\d+(-\\S+)?$"
+}
+
+action "On master branch" {
+  uses = "actions/bin/filter@master"
+  args = "branch master"
+}

.gitignore

@@ -1,5 +1,6 @@
 .DS_Store
 /node_modules
+/.github/actions/*/node_modules
 /packages/*/node_modules
 /packages/*/LICENSE
 !/packages/babel-parser/LICENSE
@@ -15,6 +16,7 @@ coverage
 dist
 /.package.json
 package-lock.json
+!/.github/actions/*/package-lock.json
 
 /packages/babel-runtime/helpers/*.js
 !/packages/babel-runtime/helpers/toArray.js

.prettierignore

@@ -1,2 +1,5 @@
 package.json
 packages/babel-preset-env/data
+packages/*/test/fixtures/**/input.*
+packages/*/test/fixtures/**/exec.*
+packages/*/test/fixtures/**/output.*

.travis.yml

@@ -1,6 +1,5 @@
 git:
   depth: 5
-sudo: false
 language: node_js
 cache:
   yarn: true
@@ -20,17 +19,18 @@ before_install:
 
 install:
   # the `make test-ci` script runs this command already
-  - if [ "$JOB" != "test" ]; then yarn install; fi
+  - if [ "$JOB" != "test" ] && [ "$JOB" != "lint" ]; then yarn install; fi
+  - if [ "$JOB" = "lint" ]; then make bootstrap; fi
 
 before_script:
-  - 'if [ "$JOB" = "babel-parser-flow-tests" ]; then make bootstrap-flow; fi'
-  - 'if [ "$JOB" = "babel-parser-test262-tests" ]; then make bootstrap-test262; fi'
+  - if [ "$JOB" = "babel-parser-flow-tests" ]; then make bootstrap-flow; fi
+  - if [ "$JOB" = "babel-parser-test262-tests" ]; then make bootstrap-test262; fi
 
 script:
-  - 'if [ "$JOB" = "test" ]; then make test-ci; fi'
-  - 'if [ "$JOB" = "lint" ]; then make lint && make flow; fi'
-  - 'if [ "$JOB" = "babel-parser-flow-tests" ]; then make test-flow-ci; fi'
-  - 'if [ "$JOB" = "babel-parser-test262-tests" ]; then make test-test262-ci; fi'
+  - if [ "$JOB" = "test" ]; then make test-ci; fi
+  - if [ "$JOB" = "lint" ]; then make lint && make flow; fi
+  - if [ "$JOB" = "babel-parser-flow-tests" ]; then make test-flow-ci; fi
+  - if [ "$JOB" = "babel-parser-test262-tests" ]; then make test-test262-ci; fi
 
 matrix:
   fast_finish: true

CHANGELOG.md

@@ -15,6 +15,164 @@ See [CHANGELOG - v4](/.github/CHANGELOG-v4.md), [CHANGELOG - v5](/.github/CHANGE
 See [CHANGELOG - 6to5](/.github/CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 See [Babylon's CHANGELOG](packages/babylon/CHANGELOG.md) for the Babylon pre-7.0.0-beta.29 version changelog.
 
+## v7.2.1 (2018-12-04)
+
+This release fixes a regression introduced in v7.2.0 (https://github.com/babel/babel/issues/9120)
+
+#### :bug: Bug Fix
+* `babel-helper-create-class-features-plugin`
+  * [#9121](https://github.com/babel/babel/pull/9121) Don't use isClassPrivateMethod because it isn't supported in <7.2.0. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+
+## v7.2.0 (2018-12-03)
+
+You can read more about this release at https://babeljs.io/blog/2018/12/03/7.2.0.
+
+#### :rocket: New Feature
+* `babel-parser`
+  * [#8289](https://github.com/babel/babel/pull/8289) Implement Smart Pipeline proposal in @babel/parser. ([@mAAdhaTTah](https://github.com/mAAdhaTTah))
+* `babel-core`
+  * [#8986](https://github.com/babel/babel/pull/8986) Export @babel/parser#tokTypes in @babel/core. ([@kaicataldo](https://github.com/kaicataldo))
+* `babel-node`
+  * [#9078](https://github.com/babel/babel/pull/9078) Pass `rootMode` from `@babel/node`.. ([@wtgtybhertgeghgtwtg](https://github.com/wtgtybhertgeghgtwtg))
+* `babel-generator`, `babel-helpers`, `babel-plugin-class-features`, `babel-plugin-proposal-private-methods`, `babel-plugin-syntax-class-properties`, `babel-types`
+  * [#8654](https://github.com/babel/babel/pull/8654) Private class methods stage 3. ([@tim-mc](https://github.com/tim-mc))
+* `babel-preset-env`
+  * [#9048](https://github.com/babel/babel/pull/9048) Update mappings for node 10 in preset-env. ([@existentialism](https://github.com/existentialism))
+
+#### :bug: Bug Fix
+* `babel-parser`
+  * [#9114](https://github.com/babel/babel/pull/9114) Parse non-octals with leading zeros in non strict mode correctly. ([@danez](https://github.com/danez))
+  * [#9074](https://github.com/babel/babel/pull/9074) Disallow await inside arrow functions. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+  * [#9069](https://github.com/babel/babel/pull/9069) [flow] Allow type casts in array patterns inside arrow parameters. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+  * [#9058](https://github.com/babel/babel/pull/9058) Fix compatibility between typescript and jsx plugins in interface declarations. ([@danez](https://github.com/danez))
+  * [#9055](https://github.com/babel/babel/pull/9055) Fix bug with parsing TS generic async arrow function. ([@existentialism](https://github.com/existentialism))
+  * [#9035](https://github.com/babel/babel/pull/9035) Fix parsing typescript function types with destructuring. ([@danez](https://github.com/danez))
+* `babel-helper-fixtures`, `babel-parser`
+  * [#9113](https://github.com/babel/babel/pull/9113) Ignore empty fixture directories and fix fixtures in the parser. ([@danez](https://github.com/danez))
+* `babel-preset-env`
+  * [#9091](https://github.com/babel/babel/pull/9091) Update mapping for regex unicode plugin in preset-env. ([@existentialism](https://github.com/existentialism))
+* `babel-plugin-transform-destructuring`
+  * [#8916](https://github.com/babel/babel/pull/8916) Fix destructuring assignment in arrow functions without block. ([@RubenVerborgh](https://github.com/RubenVerborgh))
+* `babel-plugin-proposal-optional-chaining`
+  * [#9073](https://github.com/babel/babel/pull/9073) Microbouji patch/8136. ([@jridgewell](https://github.com/jridgewell))
+* `babel-core`, `babel-helper-wrap-function`, `babel-plugin-proposal-async-generator-functions`, `babel-plugin-proposal-function-sent`, `babel-plugin-transform-async-to-generator`, `babel-plugin-transform-classes`
+  * [#9039](https://github.com/babel/babel/pull/9039) Fix recursive async function expressions. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+* `babel-core`
+  * [#9034](https://github.com/babel/babel/pull/9034) Normalize presets before merging config with others.. ([@loganfsmyth](https://github.com/loganfsmyth))
+
+#### :nail_care: Polish
+* `babel-generator`
+  * [#9089](https://github.com/babel/babel/pull/9089) Remove unused variable. ([@Gcaufy](https://github.com/Gcaufy))
+* `babel-node`
+  * [#9079](https://github.com/babel/babel/pull/9079) Move `fs-readdir-recursive` and `output-file-sync` to `devDependencies` for `@babel/node`.. ([@wtgtybhertgeghgtwtg](https://github.com/wtgtybhertgeghgtwtg))
+* `babel-parser`
+  * [#9046](https://github.com/babel/babel/pull/9046) a better error message for disallowed trailing commas/additional parameters after rest elements in function params. ([@morozRed](https://github.com/morozRed))
+* `babel-*`
+  * [#8769](https://github.com/babel/babel/pull/8769) Add plugins name. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+
+#### :house: Internal
+* `babel-helper-create-class-features-plugin`, `babel-plugin-proposal-class-properties`, `babel-plugin-proposal-private-methods`
+  * [#9083](https://github.com/babel/babel/pull/9083) Make @babel/plugin-class-features a normal helper package. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+* Other
+  * [#9096](https://github.com/babel/babel/pull/9096) Add node 11 to CI and remove node 9. ([@danez](https://github.com/danez))
+  * [#9094](https://github.com/babel/babel/pull/9094) Skip minifying standalone in non-publish runs. ([@danez](https://github.com/danez))
+* `babel-types`
+  * [#9093](https://github.com/babel/babel/pull/9093) Fix warning when using prettier in code generators. ([@danez](https://github.com/danez))
+* `babel-generator`
+  * [#9089](https://github.com/babel/babel/pull/9089) Remove unused variable. ([@Gcaufy](https://github.com/Gcaufy))
+
+## v7.1.6 (2018-11-13)
+
+#### :bug: Bug Fix
+* `babel-generator`
+  * [#9003](https://github.com/babel/babel/pull/9003) Fix retainLines regression for arrow functions. ([@loganfsmyth](https://github.com/loganfsmyth))
+* `babel-types`
+  * [#8997](https://github.com/babel/babel/pull/8997) Fix cloneNode with typeAnnotation.. ([@neoziro](https://github.com/neoziro))
+* `babel-plugin-transform-flow-strip-types`, `babel-plugin-transform-react-jsx`
+  * [#8701](https://github.com/babel/babel/pull/8701) Fix "TypeError: comments is not iterable". ([@AlicanC](https://github.com/AlicanC))
+* `babel-core`
+  * [#9004](https://github.com/babel/babel/pull/9004) Fix browser files to have the same API as the nodejs ones. ([@danez](https://github.com/danez))
+* Other
+  * [#9007](https://github.com/babel/babel/pull/9007) [Types] fix generated TS/Flow comment types. ([@ljqx](https://github.com/ljqx))
+* `babel-preset-env`
+  * [#8555](https://github.com/babel/babel/pull/8555) preset-env: fix `opera` from `esmodules` target and Browserslist not used. ([@ylemkimon](https://github.com/ylemkimon))
+* `babel-plugin-proposal-decorators`, `babel-traverse`
+  * [#8970](https://github.com/babel/babel/pull/8970) [decorators] Correctly insert `_initialize(this)` after `super()`.. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+* `babel-parser`
+  * [#8972](https://github.com/babel/babel/pull/8972) Fix several edge cases with context expression state. ([@danez](https://github.com/danez))
+
+#### :nail_care: Polish
+* `babel-parser`
+  * [#8984](https://github.com/babel/babel/pull/8984) Rename primitive types to reserved types. ([@danez](https://github.com/danez))
+
+#### :house: Internal
+* [#8982](https://github.com/babel/babel/pull/8982) fix publish command [skip ci]. ([@hzoo](https://github.com/hzoo))
+* [#8988](https://github.com/babel/babel/pull/8988) Remove definition of micromatch which was removed.. ([@danez](https://github.com/danez))
+
+## v7.1.5 (2018-11-06)
+
+#### :eyeglasses: Spec Compliancy
+* `babel-parser`, `babylon`
+  * [#7727](https://github.com/babel/babel/pull/7727) Fix await in function name and parameters. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+
+#### :rocket: New Feature
+* `babel-parser`
+  * [#8828](https://github.com/babel/babel/pull/8828) Typescript: Validate tuple type element positions. ([@Retsam](https://github.com/Retsam))
+  * [#8883](https://github.com/babel/babel/pull/8883) [flow] Add support for parsing `_` as implicit instantiation in call/new. ([@jbrown215](https://github.com/jbrown215))
+* `babel-core`, `babel-generator`, `babel-parser`, `babel-plugin-syntax-typescript`, `babel-traverse`
+  * [#8448](https://github.com/babel/babel/pull/8448) Remove Babylon plugins for features already merged to the ECMAScript spec. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+* `babel-parser`, `babel-types`
+  * [#8884](https://github.com/babel/babel/pull/8884) [flow] Explicit inexact objects with `...`. ([@jbrown215](https://github.com/jbrown215))
+* `babel-preset-env`
+  * [#8898](https://github.com/babel/babel/pull/8898) Update preset-env data. ([@existentialism](https://github.com/existentialism))
+
+#### :bug: Bug Fix
+* `babel-parser`
+  * [#8956](https://github.com/babel/babel/pull/8956) Do not allow TypeCastExpressions w/o parens . ([@danez](https://github.com/danez))
+  * [#8954](https://github.com/babel/babel/pull/8954) Allow function types in type params within arrow return types. ([@danez](https://github.com/danez))
+  * [#8866](https://github.com/babel/babel/pull/8866) Closes [#8865](https://github.com/babel/babel/issues/8865). ([@byronluk](https://github.com/byronluk))
+* `babel-core`
+  * [#8910](https://github.com/babel/babel/pull/8910) Resolve babel.config.js 'babelrcRoots' values relative to the config file.. ([@loganfsmyth](https://github.com/loganfsmyth))
+  * [#8950](https://github.com/babel/babel/pull/8950) Fix message when plugin of a wrong type is passed. ([@everdimension](https://github.com/everdimension))
+* `babel-plugin-transform-block-scoping`
+  * [#8937](https://github.com/babel/babel/pull/8937) rename colliding let bindings with for loop init. ([@byronluk](https://github.com/byronluk))
+  * [#8914](https://github.com/babel/babel/pull/8914) Treat break inside block inside loop. ([@thiagoarrais](https://github.com/thiagoarrais))
+* `babel-preset-env`
+  * [#8926](https://github.com/babel/babel/pull/8926) preset-env: Edge support for arrow param destructuring. ([@benmosher](https://github.com/benmosher))
+* `babel-generator`
+  * [#8868](https://github.com/babel/babel/pull/8868) fix single-arg async arrows when retainLines=true. ([@ryanwmarsh](https://github.com/ryanwmarsh))
+* `babel-traverse`
+  * [#8880](https://github.com/babel/babel/pull/8880) fix: Expression x === 'y' && '' should not evaluate to undefined.. ([@Cyp](https://github.com/Cyp))
+
+#### :nail_care: Polish
+* [#8873](https://github.com/babel/babel/pull/8873) fixed an extra word. ([@vvyomjjain](https://github.com/vvyomjjain))
+
+## v7.1.4 (2018-10-11)
+
+Just re-published `@babel/traverse` without `**` so that it works in Node 6.
+
+## v7.1.3 (2018-10-11)
+
+#### :bug: Bug Fix
+* `babel-generator`, `babel-parser`, `babel-plugin-transform-typescript`, `babel-types`
+  * [#8720](https://github.com/babel/babel/pull/8720) Typescript - Tuple elements can be optional. ([@Retsam](https://github.com/Retsam))
+* `babel-traverse`
+  * [#8833](https://github.com/babel/babel/pull/8833) Insertafter jsx fix. ([@kevintab95](https://github.com/kevintab95))
+* `babel-parser`
+  * [#8830](https://github.com/babel/babel/pull/8830) Correct handling of newline after async with paren-less arrow func. ([@Retsam](https://github.com/Retsam))
+  * [#8756](https://github.com/babel/babel/pull/8756) class private methods and properties: should not allow spaces between # and identifier. ([@macabeus](https://github.com/macabeus))
+  * [#8804](https://github.com/babel/babel/pull/8804) Fix parsing of slash after class expression. ([@existentialism](https://github.com/existentialism))
+  * [#8767](https://github.com/babel/babel/pull/8767) [decorators] [typescript] Parse type parameters. ([@nicolo-ribaudo](https://github.com/nicolo-ribaudo))
+  * [#8792](https://github.com/babel/babel/pull/8792) Fix perf issue in typescript parser plugin. ([@matthewrobertson](https://github.com/matthewrobertson))
+* `babel-generator`, `babel-parser`, `babel-plugin-transform-typescript`, `babel-types`
+  * [#8805](https://github.com/babel/babel/pull/8805) Typescript - Tuples can include rest elements. ([@Retsam](https://github.com/Retsam))
+* `babel-types`
+  * [#8791](https://github.com/babel/babel/pull/8791) types: allow jsxEmptyExpression inside jsxExpressionContainer. ([@tvooo](https://github.com/tvooo))
+* `babel-plugin-transform-modules-systemjs`
+  * [#8820](https://github.com/babel/babel/pull/8820) System module format - fixes function hoisting failure case. ([@guybedford](https://github.com/guybedford))
+* `babel-plugin-transform-destructuring`
+  * [#8793](https://github.com/babel/babel/pull/8793) Ensure destructuring's computed key handling matches object-rest-spread. ([@existentialism](https://github.com/existentialism))
+
 ## 7.1.2 (2018-09-28)
 
 Same as v7.1.1, except compiled against Node 6 instead of Node 8 by accident (e.g had `async functions`).

Gulpfile.js

@@ -6,7 +6,7 @@ const chalk = require("chalk");
 const newer = require("gulp-newer");
 const babel = require("gulp-babel");
 const gulpWatch = require("gulp-watch");
-const gutil = require("gulp-util");
+const fancyLog = require("fancy-log");
 const filter = require("gulp-filter");
 const gulp = require("gulp");
 const path = require("path");
@@ -17,8 +17,7 @@ const source = require("vinyl-source-stream");
 const buffer = require("vinyl-buffer");
 const rollupBabel = require("rollup-plugin-babel");
 const rollupNodeResolve = require("rollup-plugin-node-resolve");
-const registerStandalonePackageTask = require("./scripts/gulp-tasks")
-  .registerStandalonePackageTask;
+const { registerStandalonePackageTask } = require("./scripts/gulp-tasks");
 
 const sources = ["codemods", "packages"];
 
@@ -38,7 +37,7 @@ function getIndexFromPackage(name) {
 
 function compilationLogger(rollup) {
   return through.obj(function(file, enc, callback) {
-    gutil.log(
+    fancyLog(
       `Compiling '${chalk.cyan(file.relative)}'${
         rollup ? " with rollup " : ""
       }...`
@@ -50,7 +49,7 @@ function compilationLogger(rollup) {
 function errorsLogger() {
   return plumber({
     errorHandler(err) {
-      gutil.log(err.stack);
+      fancyLog(err.stack);
     },
   });
 }
@@ -138,7 +137,7 @@ registerStandalonePackageTask(
   "babel",
   "Babel",
   path.join(__dirname, "packages"),
-  require("./packages/babel-core/package.json").version
+  require("./packages/babel-standalone/package.json").version
 );
 
 const presetEnvWebpackPlugins = [
@@ -167,6 +166,6 @@ registerStandalonePackageTask(
   "babel-preset-env",
   "babelPresetEnv",
   path.join(__dirname, "packages"),
-  require("./packages/babel-preset-env/package.json").version,
+  require("./packages/babel-preset-env-standalone/package.json").version,
   presetEnvWebpackPlugins
 );

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2014-2018 Sebastian McKenzie and other contributors
+Copyright (c) 2014-present Sebastian McKenzie and other contributors
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the

Makefile

@@ -1,6 +1,6 @@
 MAKEFLAGS = -j1
-FLOW_COMMIT = e192e1a4793dd8e43415fbfe8046d832cb513c8b
-TEST262_COMMIT = 238c88d4a084d9928372954e2fec54af2c951281
+FLOW_COMMIT = 2ac56861e3ceff9ca406ae586fbafb3480c6c0b7
+TEST262_COMMIT = 4f1155c566a222238fd86f179c6635ecb4c289bb
 
 # Fix color output until TravisCI fixes https://github.com/travis-ci/travis-ci/issues/7967
 export FORCE_COLOR = true
@@ -15,8 +15,8 @@ build: clean clean-lib
 	# call build again as the generated files might need to be compiled again.
 	./node_modules/.bin/gulp build
 	# generate flow and typescript typings
-	node scripts/generators/flow.js > ./packages/babel-types/lib/index.js.flow
-	node scripts/generators/typescript.js > ./packages/babel-types/lib/index.d.ts
+	node packages/babel-types/scripts/generators/flow.js > ./packages/babel-types/lib/index.js.flow
+	node packages/babel-types/scripts/generators/typescript.js > ./packages/babel-types/lib/index.d.ts
 ifneq ("$(BABEL_COVERAGE)", "true")
 	make build-standalone
 	make build-preset-env-standalone
@@ -28,6 +28,12 @@ build-standalone:
 build-preset-env-standalone:
 	./node_modules/.bin/gulp build-babel-preset-env-standalone
 
+prepublish-build-standalone:
+	BABEL_ENV=production IS_PUBLISH=true ./node_modules/.bin/gulp build-babel-standalone
+
+prepublish-build-preset-env-standalone:
+	BABEL_ENV=production IS_PUBLISH=true ./node_modules/.bin/gulp build-babel-preset-env-standalone
+
 build-dist: build
 	cd packages/babel-polyfill; \
 	scripts/build-dist.sh
@@ -40,7 +46,8 @@ watch: clean clean-lib
 	# development too.
 	BABEL_ENV=development ./node_modules/.bin/gulp build-no-bundle
 	node ./packages/babel-types/scripts/generateTypeHelpers.js
-	node scripts/generators/flow.js > ./packages/babel-types/lib/index.js.flow
+	node packages/babel-types/scripts/generators/flow.js > ./packages/babel-types/lib/index.js.flow
+	node packages/babel-types/scripts/generators/typescript.js > ./packages/babel-types/lib/index.d.ts
 	BABEL_ENV=development ./node_modules/.bin/gulp watch
 
 flow:
@@ -96,7 +103,7 @@ test-flow-update-whitelist:
 bootstrap-test262:
 	rm -rf ./build/test262
 	mkdir -p ./build
-	git clone --branch=master --single-branch --shallow-since=2018-11-01 https://github.com/tc39/test262.git ./build/test262
+	git clone --branch=master --single-branch --shallow-since=2010-01-10 https://github.com/tc39/test262.git ./build/test262
 	cd build/test262 && git checkout $(TEST262_COMMIT)
 
 test-test262:
@@ -115,7 +122,7 @@ prepublish-build:
 	rm -rf packages/babel-runtime/helpers
 	rm -rf packages/babel-runtime-corejs2/helpers
 	rm -rf packages/babel-runtime-corejs2/core-js
-	BABEL_ENV=production IS_PUBLISH=true make build-dist
+	BABEL_ENV=production make build-dist
 	make clone-license
 
 prepublish:
@@ -123,9 +130,12 @@ prepublish:
 	make prepublish-build
 	make test
 
+new-version:
+	./node_modules/.bin/lerna version --force-publish="@babel/runtime,@babel/runtime-corejs2,@babel/standalone,@babel/preset-env-standalone"
+
+# NOTE: Run make new-version first
 publish: prepublish
-	# --only-explicit-updates
-	./node_modules/.bin/lerna publish --force-publish="@babel/runtime,@babel/runtime-corejs2" --dangerously-only-publish-explicit-updates-this-is-a-custom-flag-for-babel-and-you-should-not-be-using-it-just-deal-with-more-packages-being-published-it-is-not-a-big-deal
+	./node_modules/.bin/lerna publish from-git --require-scripts
 	make clean
 
 bootstrap: clean-all

README.md

@@ -8,12 +8,16 @@
   The compiler for writing next generation JavaScript.
 </p>
 
+<p align="center">
+    <a href="https://www.npmjs.com/package/@babel/core"><img alt="v7 npm Downloads" src="https://img.shields.io/npm/dm/@babel/core.svg?maxAge=43200&label=v7%20downloads"></a>
+  <a href="https://www.npmjs.com/package/babel-core"><img alt="v6 npm Downloads" src="https://img.shields.io/npm/dm/babel-core.svg?maxAge=43200&label=v6%20downloads"></a>
+</p>
 <p align="center">
   <a href="https://travis-ci.org/babel/babel"><img alt="Travis Status" src="https://img.shields.io/travis/babel/babel/master.svg?label=travis&maxAge=43200"></a>
   <a href="https://circleci.com/gh/babel/babel"><img alt="CircleCI Status" src="https://img.shields.io/circleci/project/github/babel/babel/master.svg?label=circle&maxAge=43200"></a>
   <a href="https://codecov.io/github/babel/babel"><img alt="Coverage Status" src="https://img.shields.io/codecov/c/github/babel/babel/master.svg?maxAge=43200"></a>
   <a href="https://slack.babeljs.io/"><img alt="Slack Status" src="https://slack.babeljs.io/badge.svg"></a>
-  <a href="https://www.npmjs.com/package/babel-core"><img alt="npm Downloads" src="https://img.shields.io/npm/dm/babel-core.svg?maxAge=43200"></a>
+  <a href="https://twitter.com/intent/follow?screen_name=babeljs"><img alt="Follow on Twitter" src="https://img.shields.io/twitter/follow/babeljs.svg?style=social&label=Follow"></a>
 </p>
 
 <h2 align="center">Supporting Babel</h2>
@@ -48,35 +52,15 @@ Become a sponsor and get your logo on our README on Github with a link to your s
   <a href="https://opencollective.com/babel/sponsor/12/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/12/avatar.svg"></a>
   <a href="https://opencollective.com/babel/sponsor/13/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/13/avatar.svg"></a>
   <a href="https://opencollective.com/babel/sponsor/14/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/14/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/15/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/15/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/16/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/16/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/17/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/17/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/18/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/18/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/19/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/19/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/20/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/20/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/21/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/21/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/22/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/22/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/23/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/23/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/24/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/24/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/25/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/25/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/26/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/26/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/27/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/27/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/28/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/28/avatar.svg"></a>
-  <a href="https://opencollective.com/babel/sponsor/29/website" target="_blank"><img src="https://opencollective.com/babel/sponsor/29/avatar.svg"></a>
 
 ## Patreon Sponsors
 
 Become a sponsor and get your logo on our README on Github with a link to your site. [[Become a sponsor](https://www.patreon.com/henryzhu)]
 
-## Silver
-
-<a href="https://issue.sh/?utm_medium=github&utm_campaign=babel" target="_blank"><img src="https://user-images.githubusercontent.com/5557143/43912065-c8cdff78-9c33-11e8-829a-0b4166ccc215.png"></a>
-
 ## Bronze
 
-<a href="http://teamextension.io/" target="_blank"><img src="https://teamextension.io/dist/img/logo/te-logo-compact.png" height="64"></a>
-<a href="https://webflow.com/" target="_blank"><img src="https://opencollective.com/proxy/images/?src=https%3A%2F%2Fopencollective-production.s3-us-west-1.amazonaws.com%2F4a5024b0-8cf2-11e7-b1a2-b30b1de1463c.png&height=64"></a>
-<p><a href="https://twitter.com/mikesherov">Mike Sherov</a></p>
+<a href="https://webflow.com" target="_blank"><img src="https://opencollective.com/proxy/images/?src=https%3A%2F%2Fopencollective-production.s3-us-west-1.amazonaws.com%2F4a5024b0-8cf2-11e7-b1a2-b30b1de1463c.png&height=64"></a>
+<a href="https://issuehunt.io" target="_blank"><img src="https://github.com/BoostIO/issuehunt-materials/blob/master/v1/issuehunt-logo-and-word-v1.png?raw=true" height="64"></a>
 
 ## Intro
 
@@ -103,7 +87,7 @@ Try it out at our [REPL](https://babeljs.io/repl/build/master#?code_lz=NoRgNATGD
 
 ### Who maintains Babel?
 
-Mostly a handful of volunteers! Please check out our [team page](https://babeljs.io/team)!
+Mostly a handful of volunteers, funded by you! Please check out our [team page](https://babeljs.io/team)!
 
 ### Looking for support?
 

babel.config.js

@@ -14,12 +14,16 @@ module.exports = function(api) {
   let convertESM = true;
   let ignoreLib = true;
   let includeRuntime = false;
+  const nodeVersion = "6.9";
 
   switch (env) {
     // Configs used during bundling builds.
     case "babel-parser":
       convertESM = false;
       ignoreLib = false;
+      envOpts.targets = {
+        node: nodeVersion,
+      };
       break;
     case "standalone":
       convertESM = false;
@@ -29,7 +33,7 @@ module.exports = function(api) {
     case "production":
       // Config during builds before publish.
       envOpts.targets = {
-        node: "6.9",
+        node: nodeVersion,
       };
       break;
     case "development":

codecov.yml

@@ -8,3 +8,5 @@ coverage:
         target: "80%"
     patch:
       enabled: false
+ignore:
+  - packages/babel-types/src/*/generated/index.js

lerna.json

@@ -1,6 +1,5 @@
 {
-  "lerna": "2.11.0",
-  "version": "7.2.0",
+  "version": "7.3.3",
   "changelog": {
     "repo": "babel/babel",
     "cacheDir": ".changelog",
@@ -14,21 +13,21 @@
       "PR: Internal :house:": ":house: Internal"
     }
   },
-  "commands": {
+  "command": {
     "publish": {
-      "ignore": [
+      "ignoreChanges": [
         "*.md",
-        "*.json",
         "*.txt",
         "test/**",
         "codemods/**",
-        "package.json"
+        "# We ignore every JSON file, except for built-in-modules, built-ins and plugins defined in babel-preset-env/data.",
+        "@(!(built-in-modules|built-ins|plugins)).json"
       ]
     }
   },
   "packages": [
-    "packages/*",
-    "codemods/*"
+    "codemods/*",
+    "packages/*"
   ],
   "npmClient": "yarn",
   "npmClientArgs": [

package.json

@@ -9,55 +9,55 @@
     "test": "make test"
   },
   "devDependencies": {
-    "@babel/cli": "^7.1.5",
-    "@babel/core": "^7.1.6",
-    "@babel/plugin-proposal-class-properties": "^7.1.0",
-    "@babel/plugin-proposal-export-namespace-from": "^7.0.0",
-    "@babel/plugin-proposal-numeric-separator": "^7.0.0",
-    "@babel/plugin-transform-modules-commonjs": "^7.1.0",
-    "@babel/plugin-transform-runtime": "^7.1.0",
-    "@babel/preset-env": "^7.1.6",
+    "@babel/cli": "^7.2.3",
+    "@babel/core": "^7.2.2",
+    "@babel/eslint-plugin-development": "^1.0.1",
+    "@babel/plugin-proposal-class-properties": "^7.3.0",
+    "@babel/plugin-proposal-export-namespace-from": "^7.2.0",
+    "@babel/plugin-proposal-numeric-separator": "^7.2.0",
+    "@babel/plugin-transform-modules-commonjs": "^7.2.0",
+    "@babel/plugin-transform-runtime": "^7.2.0",
+    "@babel/preset-env": "^7.3.1",
     "@babel/preset-flow": "^7.0.0",
     "@babel/register": "^7.0.0",
-    "@babel/runtime": "^7.1.5",
-    "babel-core": "^7.0.0-0",
-    "babel-eslint": "^10.0.1",
-    "babel-jest": "^23.6.0",
-    "babel-loader": "^8.0.4",
-    "babel-plugin-transform-charcodes": "^0.1.0",
-    "browserify": "^16.2.2",
+    "@babel/runtime": "^7.3.1",
+    "babel-eslint": "^11.0.0-beta.0",
+    "babel-jest": "^24.0.0",
+    "babel-loader": "^8.0.5",
+    "babel-plugin-transform-charcodes": "^0.2.0",
+    "browserify": "^16.2.3",
     "bundle-collapser": "^1.2.1",
     "chalk": "^2.3.2",
-    "charcodes": "^0.1.0",
+    "charcodes": "^0.2.0",
     "derequire": "^2.0.2",
+    "duplicate-package-checker-webpack-plugin": "^2.1.0",
     "enhanced-resolve": "^3.0.0",
-    "eslint": "^5.9.0",
+    "eslint": "^5.12.1",
     "eslint-config-babel": "^8.0.2",
-    "eslint-plugin-flowtype": "^3.2.0",
-    "eslint-plugin-local-rules": "0.1.0",
-    "eslint-plugin-prettier": "^3.0.0",
-    "flow-bin": "^0.82.0",
-    "graceful-fs": "^4.1.11",
+    "eslint-plugin-flowtype": "^3.2.1",
+    "eslint-plugin-prettier": "^3.0.1",
+    "fancy-log": "^1.3.3",
+    "flow-bin": "^0.92.1",
+    "graceful-fs": "^4.1.15",
     "gulp": "^4.0.0",
     "gulp-babel": "^8.0.0",
     "gulp-filter": "^5.1.0",
     "gulp-newer": "^1.0.0",
-    "gulp-plumber": "^1.2.0",
+    "gulp-plumber": "^1.2.1",
     "gulp-rename": "^1.4.0",
     "gulp-uglify": "^3.0.1",
-    "gulp-util": "^3.0.7",
     "gulp-watch": "^5.0.1",
-    "husky": "^1.2.0",
-    "jest": "^23.6.0",
-    "lerna": "^2.11.0",
+    "husky": "^1.3.1",
+    "jest": "^24.0.0",
+    "lerna": "^3.6.0",
     "lerna-changelog": "^0.5.0",
     "lint-staged": "^8.1.0",
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "merge-stream": "^1.0.1",
     "output-file-sync": "^2.0.0",
-    "prettier": "^1.15.2",
+    "prettier": "^1.16.1",
     "pump": "^3.0.0",
-    "rimraf": "^2.4.3",
+    "rimraf": "^2.6.3",
     "rollup-plugin-babel": "^4.0.0-beta.0",
     "rollup-plugin-node-resolve": "^3.0.2",
     "rollup-stream": "^1.24.1",
@@ -69,6 +69,9 @@
     "webpack-dependency-suite": "^2.4.4",
     "webpack-stream": "^4.0.0"
   },
+  "resolutions": {
+    "@lerna/**/@lerna/collect-updates": "https://github.com/nicolo-ribaudo/lerna.git#babel-collect-updates"
+  },
   "engines": {
     "node": ">= 6.9.0 < 12.0.0",
     "npm": ">= 3.x <= 6.x",
@@ -105,7 +108,9 @@
       "_browser\\.js"
     ],
     "testEnvironment": "node",
-    "setupTestFrameworkScriptFile": "<rootDir>/test/testSetupFile.js",
+    "setupFilesAfterEnv": [
+      "<rootDir>/test/testSetupFile.js"
+    ],
     "transformIgnorePatterns": [
       "/node_modules/",
       "<rootDir>/packages/babel-standalone/babel(\\.min)?\\.js",
@@ -124,6 +129,10 @@
       "/test/tmp/",
       "/test/__data__/",
       "<rootDir>/build/"
-    ]
-  }
+    ],
+    "moduleNameMapper": {
+      "^@babel/([a-zA-Z0-9_-]+)$": "<rootDir>/packages/babel-$1/"
+    }
+  },
+  "dependencies": {}
 }

packages/babel-cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/cli",
-  "version": "7.2.0",
+  "version": "7.2.3",
   "description": "Babel command line.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",

packages/babel-cli/src/babel/options.js

@@ -22,7 +22,7 @@ commander.option(
   "comma-separated list of plugin names",
   collect,
 );
-commander.option("--config-file [path]", "Path a to .babelrc file to use");
+commander.option("--config-file [path]", "Path to a .babelrc file to use");
 commander.option(
   "--env-name [name]",
   "The name of the 'env' to use when loading configs and plugins. " +

packages/babel-core/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/core",
-  "version": "7.2.0",
+  "version": "7.3.3",
   "description": "Babel compiler core.",
   "main": "lib/index.js",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
@@ -34,16 +34,16 @@
   },
   "dependencies": {
     "@babel/code-frame": "^7.0.0",
-    "@babel/generator": "^7.2.0",
+    "@babel/generator": "^7.3.3",
     "@babel/helpers": "^7.2.0",
-    "@babel/parser": "^7.2.0",
-    "@babel/template": "^7.1.2",
-    "@babel/traverse": "^7.1.6",
-    "@babel/types": "^7.2.0",
+    "@babel/parser": "^7.3.3",
+    "@babel/template": "^7.2.2",
+    "@babel/traverse": "^7.2.2",
+    "@babel/types": "^7.3.3",
     "convert-source-map": "^1.1.0",
     "debug": "^4.1.0",
     "json5": "^2.1.0",
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "resolve": "^1.3.2",
     "semver": "^5.4.1",
     "source-map": "^0.5.0"

packages/babel-core/src/config/caching.js

@@ -54,6 +54,7 @@ function makeCachedFunction<
   ArgT,
   ResultT,
   SideChannel,
+  // $FlowIssue https://github.com/facebook/flow/issues/4528
   Cache: CacheMap<ArgT, ResultT, SideChannel>,
 >(
   callCache: Cache,

packages/babel-core/src/config/files/configuration.js

@@ -10,7 +10,7 @@ import {
   makeWeakCache,
   type CacheConfigurator,
 } from "../caching";
-import makeAPI from "../helpers/config-api";
+import makeAPI, { type PluginAPI } from "../helpers/config-api";
 import { makeStaticFileCache } from "./utils";
 import pathPatternToRegex from "../pattern-to-regex";
 import type { FilePackageData, RelativeConfig, ConfigFile } from "./types";
@@ -150,7 +150,7 @@ const LOADING_CONFIGS = new Set();
 
 const readConfigJS = makeStrongCache(
   (
-    filepath,
+    filepath: string,
     cache: CacheConfigurator<{
       envName: string,
       caller: CallerMetadata | void,
@@ -193,7 +193,7 @@ const readConfigJS = makeStrongCache(
     }
 
     if (typeof options === "function") {
-      options = options(makeAPI(cache));
+      options = ((options: any): (api: PluginAPI) => {})(makeAPI(cache));
 
       if (!cache.configured()) throwConfigError();
     }

packages/babel-core/src/config/validation/options.js

@@ -350,7 +350,7 @@ function validateNested(loc: NestingPath, opts: {}) {
       NONPRESET_VALIDATORS[key] ||
       BABELRC_VALIDATORS[key] ||
       ROOT_VALIDATORS[key] ||
-      throwUnknownError;
+      (throwUnknownError: Validator<void>);
 
     validator(optLoc, opts[key]);
   });

packages/babel-core/src/transformation/index.js

@@ -131,6 +131,7 @@ function isThenable(val: mixed): boolean {
   return (
     !!val &&
     (typeof val === "object" || typeof val === "function") &&
+    !!val.then &&
     typeof val.then === "function"
   );
 }

packages/babel-generator/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/generator",
-  "version": "7.2.0",
+  "version": "7.3.3",
   "description": "Turns an AST into code.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -14,14 +14,14 @@
     "lib"
   ],
   "dependencies": {
-    "@babel/types": "^7.2.0",
+    "@babel/types": "^7.3.3",
     "jsesc": "^2.5.1",
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "source-map": "^0.5.0",
     "trim-right": "^1.0.1"
   },
   "devDependencies": {
     "@babel/helper-fixtures": "^7.2.0",
-    "@babel/parser": "^7.2.0"
+    "@babel/parser": "^7.3.3"
   }
 }

packages/babel-generator/src/generators/base.js

@@ -50,8 +50,35 @@ export function Directive(node: Object) {
   this.semicolon();
 }
 
+// These regexes match an even number of \ followed by a quote
+const unescapedSingleQuoteRE = /(?:^|[^\\])(?:\\\\)*'/;
+const unescapedDoubleQuoteRE = /(?:^|[^\\])(?:\\\\)*"/;
+
+export function DirectiveLiteral(node: Object) {
+  const raw = this.getPossibleRaw(node);
+  if (raw != null) {
+    this.token(raw);
+    return;
+  }
+
+  const { value } = node;
+
+  // NOTE: In directives we can't change escapings,
+  // because they change the behavior.
+  // e.g. "us\x65 string" (\x65 is e) is not a "use strict" directive.
+
+  if (!unescapedDoubleQuoteRE.test(value)) {
+    this.token(`"${value}"`);
+  } else if (!unescapedSingleQuoteRE.test(value)) {
+    this.token(`'${value}'`);
+  } else {
+    throw new Error(
+      "Malformed AST: it is not possible to print a directive containing" +
+        " both unescaped single and double quotes.",
+    );
+  }
+}
+
 export function InterpreterDirective(node: Object) {
   this.token(`#!${node.value}\n`);
 }
-
-export { StringLiteral as DirectiveLiteral } from "./types";

packages/babel-generator/src/generators/types.js

@@ -151,3 +151,15 @@ export function BigIntLiteral(node: Object) {
   }
   this.token(node.value);
 }
+
+export function PipelineTopicExpression(node: Object) {
+  this.print(node.expression, node);
+}
+
+export function PipelineBareFunction(node: Object) {
+  this.print(node.callee, node);
+}
+
+export function PipelinePrimaryTopicReference() {
+  this.token("#");
+}

packages/babel-generator/src/generators/typescript.js

@@ -476,6 +476,21 @@ export function TSModuleBlock(node) {
   this.tsPrintBraced(node.body, node);
 }
 
+export function TSImportType(node) {
+  const { argument, qualifier, typeParameters } = node;
+  this.word("import");
+  this.token("(");
+  this.print(argument, node);
+  this.token(")");
+  if (qualifier) {
+    this.token(".");
+    this.print(qualifier, node);
+  }
+  if (typeParameters) {
+    this.print(typeParameters, node);
+  }
+}
+
 export function TSImportEqualsDeclaration(node) {
   const { isExport, id, moduleReference } = node;
   if (isExport) {

packages/babel-generator/test/fixtures/escapes/jsonEscape/input.js

@@ -1 +1,2 @@
+0; // Not a directive
 "©";

packages/babel-generator/test/fixtures/escapes/jsonEscape/output.js

@@ -1 +1,2 @@
+0;// Not a directive
 "\u00A9";

packages/babel-generator/test/fixtures/flow/interface-types/input.js

@@ -1,3 +1,4 @@
 type A = interface { p: string };
 type B = interface extends X { p: string };
 type C = interface extends X, Y { p: string };
+type D = interface extends X.Y<Z> { p: string };

packages/babel-generator/test/fixtures/flow/interface-types/output.js

@@ -6,4 +6,7 @@ type B = interface extends X {
 };
 type C = interface extends X, Y {
   p: string
-};
+};
+type D = interface extends X.Y<Z> {
+  p: string
+};

packages/babel-generator/test/fixtures/flow/type-alias/input.js

@@ -14,3 +14,5 @@ type overloads =
 ;
 
 type func = string => string;
+
+type D = X.Y<Z>;

packages/babel-generator/test/fixtures/flow/type-alias/output.js

@@ -9,3 +9,4 @@ type union = {
 };
 type overloads = (x: string) => number & (x: number) => string;
 type func = (string) => string;
+type D = X.Y<Z>;

packages/babel-generator/test/fixtures/types/PipelineBareFunction/input.js

@@ -0,0 +1 @@
+let result = "hello" |> doubleSay |> text.capitalize |> a.b.exclaim;

packages/babel-generator/test/fixtures/types/PipelineBareFunction/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": [["pipelineOperator", { "proposal": "smart" }], "doExpressions"]
+}

packages/babel-generator/test/fixtures/types/PipelineBareFunction/output.js

@@ -0,0 +1 @@
+let result = "hello" |> doubleSay |> text.capitalize |> a.b.exclaim;

packages/babel-generator/test/fixtures/types/PipelineTopicExpression/input.js

@@ -0,0 +1,8 @@
+value |> # + 1;
+value |> 1 + #;
+value |> do {
+  #;
+};
+value |> do {
+  if (yes) #;
+};

packages/babel-generator/test/fixtures/types/PipelineTopicExpression/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": [["pipelineOperator", { "proposal": "smart" }], "doExpressions"]
+}

packages/babel-generator/test/fixtures/types/PipelineTopicExpression/output.js

@@ -0,0 +1,8 @@
+value |> # + 1;
+value |> 1 + #;
+value |> do {
+  #;
+};
+value |> do {
+  if (yes) #;
+};

packages/babel-generator/test/fixtures/typescript/types-import-type/input.js

@@ -0,0 +1,3 @@
+let x: typeof import('./x');
+let Y: import('./y').Y;
+let z: import("/z").foo.bar<string>;

packages/babel-generator/test/fixtures/typescript/types-import-type/output.js

@@ -0,0 +1,3 @@
+let x: typeof import('./x');
+let Y: import('./y').Y;
+let z: import("/z").foo.bar<string>;

packages/babel-generator/test/index.js

@@ -384,6 +384,48 @@ describe("programmatic generation", function() {
   [key: any]: number
 }`);
   });
+
+  describe("directives", function() {
+    it("preserves escapes", function() {
+      const directive = t.directive(
+        t.directiveLiteral(String.raw`us\x65 strict`),
+      );
+      const output = generate(directive).code;
+
+      expect(output).toBe(String.raw`"us\x65 strict";`);
+    });
+
+    it("preserves escapes in minified output", function() {
+      // https://github.com/babel/babel/issues/4767
+
+      const directive = t.directive(t.directiveLiteral(String.raw`foo\n\t\r`));
+      const output = generate(directive, { minified: true }).code;
+
+      expect(output).toBe(String.raw`"foo\n\t\r";`);
+    });
+
+    it("unescaped single quote", function() {
+      const directive = t.directive(t.directiveLiteral(String.raw`'\'\"`));
+      const output = generate(directive).code;
+
+      expect(output).toBe(String.raw`"'\'\"";`);
+    });
+
+    it("unescaped double quote", function() {
+      const directive = t.directive(t.directiveLiteral(String.raw`"\'\"`));
+      const output = generate(directive).code;
+
+      expect(output).toBe(String.raw`'"\'\"';`);
+    });
+
+    it("unescaped single and double quotes together throw", function() {
+      const directive = t.directive(t.directiveLiteral(String.raw`'"`));
+
+      expect(() => {
+        generate(directive);
+      }).toThrow();
+    });
+  });
 });
 
 describe("CodeGenerator", function() {

packages/babel-helper-builder-react-jsx/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/helper-builder-react-jsx",
-  "version": "7.0.0",
+  "version": "7.3.0",
   "description": "Helper function to build react jsx",
   "repository": "https://github.com/babel/babel/tree/master/packages/babel-helper-builder-react-jsx",
   "license": "MIT",
@@ -9,7 +9,7 @@
   },
   "main": "lib/index.js",
   "dependencies": {
-    "@babel/types": "^7.0.0",
+    "@babel/types": "^7.3.0",
     "esutils": "^2.0.0"
   }
 }

packages/babel-helper-builder-react-jsx/src/index.js

@@ -19,6 +19,13 @@ You can turn on the 'throwIfNamespace' flag to bypass this warning.`,
       );
     }
   };
+
+  visitor.JSXSpreadChild = function(path) {
+    throw path.buildCodeFrameError(
+      "Spread children are not supported in React.",
+    );
+  };
+
   visitor.JSXElement = {
     exit(path, file) {
       const callExpr = buildElementCall(path, file);

packages/babel-helper-create-class-features-plugin/README.md

@@ -1,19 +1,19 @@
-# @babel/plugin-class-features
+# @babel/helper-create-class-features-plugin
 
 > Compile class public and private fields, private methods and decorators to ES6
 
-See our website [@babel/plugin-class-features](https://babeljs.io/docs/en/next/babel-plugin-class-features.html) for more information.
+See our website [@babel/helper-create-class-features-plugin](https://babeljs.io/docs/en/next/babel-helper-create-class-features-plugin.html) for more information.
 
 ## Install
 
 Using npm:
 
 ```sh
-npm install --save-dev @babel/plugin-class-features
+npm install --save-dev @babel/helper-create-class-features-plugin
 ```
 
 or using yarn:
 
 ```sh
-yarn add @babel/plugin-class-features --dev
+yarn add @babel/helper-create-class-features-plugin --dev
 ```

packages/babel-helper-create-class-features-plugin/package.json

@@ -1,10 +1,10 @@
 {
   "name": "@babel/helper-create-class-features-plugin",
-  "version": "7.2.0",
+  "version": "7.3.2",
   "author": "The Babel Team (https://babeljs.io/team)",
   "license": "MIT",
   "description": "Compile class public and private fields, private methods and decorators to ES6",
-  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-class-features",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-helper-create-class-features-plugin",
   "main": "lib/index.js",
   "publishConfig": {
     "access": "public"
@@ -18,13 +18,14 @@
     "@babel/helper-member-expression-to-functions": "^7.0.0",
     "@babel/helper-optimise-call-expression": "^7.0.0",
     "@babel/helper-plugin-utils": "^7.0.0",
-    "@babel/helper-replace-supers": "^7.1.0"
+    "@babel/helper-replace-supers": "^7.2.3",
+    "@babel/helper-split-export-declaration": "^7.0.0"
   },
   "peerDependencies": {
     "@babel/core": "^7.0.0"
   },
   "devDependencies": {
-    "@babel/core": "^7.2.0",
+    "@babel/core": "^7.2.2",
     "@babel/helper-plugin-test-runner": "^7.0.0"
   }
 }

packages/babel-helper-create-class-features-plugin/src/decorators.js

@@ -1,3 +1,164 @@
-export function hasDecorators(path) {
-  return !!(path.node.decorators && path.node.decorators.length);
+import { types as t, template } from "@babel/core";
+import ReplaceSupers from "@babel/helper-replace-supers";
+import nameFunction from "@babel/helper-function-name";
+
+export function hasOwnDecorators(node) {
+  return !!(node.decorators && node.decorators.length);
+}
+
+export function hasDecorators(node) {
+  return hasOwnDecorators(node) || node.body.body.some(hasOwnDecorators);
+}
+
+function prop(key, value) {
+  if (!value) return null;
+  return t.objectProperty(t.identifier(key), value);
+}
+
+function method(key, body) {
+  return t.objectMethod(
+    "method",
+    t.identifier(key),
+    [],
+    t.blockStatement(body),
+  );
+}
+
+function takeDecorators(node) {
+  let result;
+  if (node.decorators && node.decorators.length > 0) {
+    result = t.arrayExpression(
+      node.decorators.map(decorator => decorator.expression),
+    );
+  }
+  node.decorators = undefined;
+  return result;
+}
+
+function getKey(node) {
+  if (node.computed) {
+    return node.key;
+  } else if (t.isIdentifier(node.key)) {
+    return t.stringLiteral(node.key.name);
+  } else {
+    return t.stringLiteral(String(node.key.value));
+  }
+}
+
+// NOTE: This function can be easily bound as .bind(file, classRef, superRef)
+//       to make it easier to use it in a loop.
+function extractElementDescriptor(/* this: File, */ classRef, superRef, path) {
+  const { node, scope } = path;
+  const isMethod = path.isClassMethod();
+
+  if (path.isPrivate()) {
+    throw path.buildCodeFrameError(
+      `Private ${
+        isMethod ? "methods" : "fields"
+      } in decorated classes are not supported yet.`,
+    );
+  }
+
+  new ReplaceSupers(
+    {
+      methodPath: path,
+      methodNode: node,
+      objectRef: classRef,
+      isStatic: node.static,
+      superRef,
+      scope,
+      file: this,
+    },
+    true,
+  ).replace();
+
+  const properties = [
+    prop("kind", t.stringLiteral(isMethod ? node.kind : "field")),
+    prop("decorators", takeDecorators(node)),
+    prop("static", node.static && t.booleanLiteral(true)),
+    prop("key", getKey(node)),
+  ].filter(Boolean);
+
+  if (isMethod) {
+    const id = node.computed ? null : node.key;
+    t.toExpression(node);
+    properties.push(prop("value", nameFunction({ node, id, scope }) || node));
+  } else if (node.value) {
+    properties.push(
+      method("value", template.statements.ast`return ${node.value}`),
+    );
+  } else {
+    properties.push(prop("value", scope.buildUndefinedNode()));
+  }
+
+  path.remove();
+
+  return t.objectExpression(properties);
+}
+
+function addDecorateHelper(file) {
+  try {
+    return file.addHelper("decorate");
+  } catch (err) {
+    if (err.code === "BABEL_HELPER_UNKNOWN") {
+      err.message +=
+        "\n  '@babel/plugin-transform-decorators' in non-legacy mode" +
+        " requires '@babel/core' version ^7.0.2 and you appear to be using" +
+        " an older version.";
+    }
+    throw err;
+  }
+}
+
+export function buildDecoratedClass(ref, path, elements, file) {
+  const { node, scope } = path;
+  const initializeId = scope.generateUidIdentifier("initialize");
+  const isDeclaration = node.id && path.isDeclaration();
+  const isStrict = path.isInStrictMode();
+  const { superClass } = node;
+
+  node.type = "ClassDeclaration";
+  if (!node.id) node.id = t.cloneNode(ref);
+
+  let superId;
+  if (superClass) {
+    superId = scope.generateUidIdentifierBasedOnNode(node.superClass, "super");
+    node.superClass = superId;
+  }
+
+  const classDecorators = takeDecorators(node);
+  const definitions = t.arrayExpression(
+    elements.map(extractElementDescriptor.bind(file, node.id, superId)),
+  );
+
+  let replacement = template.expression.ast`
+    ${addDecorateHelper(file)}(
+      ${classDecorators || t.nullLiteral()},
+      function (${initializeId}, ${superClass ? superId : null}) {
+        ${node}
+        return { F: ${t.cloneNode(node.id)}, d: ${definitions} };
+      },
+      ${superClass}
+    )
+  `;
+  let classPathDesc = "arguments.1.body.body.0";
+
+  if (!isStrict) {
+    replacement.arguments[1].body.directives.push(
+      t.directive(t.directiveLiteral("use strict")),
+    );
+  }
+
+  if (isDeclaration) {
+    replacement = template.ast`let ${ref} = ${replacement}`;
+    classPathDesc = "declarations.0.init." + classPathDesc;
+  }
+
+  return {
+    instanceNodes: [template.statement.ast`${initializeId}(this)`],
+    wrapClass(path) {
+      path.replaceWith(replacement);
+      return path.get(classPathDesc);
+    },
+  };
 }

packages/babel-helper-create-class-features-plugin/src/features.js

@@ -1,4 +1,4 @@
-import { hasDecorators } from "./decorators";
+import { hasOwnDecorators } from "./decorators";
 
 export const FEATURES = Object.freeze({
   //classes: 1 << 0,
@@ -39,17 +39,30 @@ export function isLoose(file, feature) {
 }
 
 export function verifyUsedFeatures(path, file) {
-  if (hasDecorators(path) && !hasFeature(file, FEATURES.decorators)) {
-    throw path.buildCodeFrameError("Decorators are not enabled.");
+  if (hasOwnDecorators(path.node)) {
+    if (!hasFeature(file, FEATURES.decorators)) {
+      throw path.buildCodeFrameError(
+        "Decorators are not enabled." +
+          "\nIf you are using " +
+          '["@babel/plugin-proposal-decorators", { "legacy": true }], ' +
+          'make sure it comes *before* "@babel/plugin-proposal-class-properties" ' +
+          "and enable loose mode, like so:\n" +
+          '\t["@babel/plugin-proposal-decorators", { "legacy": true }]\n' +
+          '\t["@babel/plugin-proposal-class-properties", { "loose": true }]',
+      );
+    }
+
+    if (path.isPrivate()) {
+      throw path.buildCodeFrameError(
+        `Private ${
+          path.isClassMethod() ? "methods" : "fields"
+        } in decorated classes are not supported yet.`,
+      );
+    }
   }
 
-  if (hasFeature(file, FEATURES.decorators)) {
-    throw new Error(
-      "@babel/plugin-class-features doesn't support decorators yet.",
-    );
-  }
-
-  if (path.isClassPrivateMethod()) {
+  // NOTE: We can't use path.isPrivateMethod() because it isn't supported in <7.2.0
+  if (path.isPrivate() && path.isMethod()) {
     if (!hasFeature(file, FEATURES.privateMethods)) {
       throw path.buildCodeFrameError("Class private methods are not enabled.");
     }
@@ -59,12 +72,6 @@ export function verifyUsedFeatures(path, file) {
         "@babel/plugin-class-features doesn't support class static private methods yet.",
       );
     }
-
-    if (path.node.kind !== "method") {
-      throw path.buildCodeFrameError(
-        "@babel/plugin-class-features doesn't support class private accessors yet.",
-      );
-    }
   }
 
   if (

packages/babel-helper-create-class-features-plugin/src/fields.js

@@ -6,16 +6,26 @@ import optimiseCall from "@babel/helper-optimise-call-expression";
 export function buildPrivateNamesMap(props) {
   const privateNamesMap = new Map();
   for (const prop of props) {
-    if (prop.isPrivate()) {
+    const isPrivate = prop.isPrivate();
+    const isMethod = !prop.isProperty();
+    const isInstance = !prop.node.static;
+    if (isPrivate) {
       const { name } = prop.node.key.id;
-      privateNamesMap.set(name, {
-        id: prop.scope.generateUidIdentifier(name),
-        static: !!prop.node.static,
-        method: prop.isClassPrivateMethod(),
-        methodId: prop.isClassPrivateMethod()
-          ? prop.scope.generateUidIdentifier(name)
-          : undefined,
-      });
+      const update = privateNamesMap.has(name)
+        ? privateNamesMap.get(name)
+        : {
+            id: prop.scope.generateUidIdentifier(name),
+            static: !isInstance,
+            method: isMethod,
+          };
+      if (prop.node.kind === "get") {
+        update.getId = prop.scope.generateUidIdentifier(`get_${name}`);
+      } else if (prop.node.kind === "set") {
+        update.setId = prop.scope.generateUidIdentifier(`set_${name}`);
+      } else if (prop.node.kind === "method" && isMethod && isInstance) {
+        update.methodId = prop.scope.generateUidIdentifier(name);
+      }
+      privateNamesMap.set(name, update);
     }
   }
   return privateNamesMap;
@@ -31,7 +41,7 @@ export function buildPrivateNamesNodes(privateNamesMap, loose, state) {
     // In spec mode, only instance fields need a "private name" initializer
     // because static fields are directly assigned to a variable in the
     // buildPrivateStaticFieldInitSpec function.
-    const { id, static: isStatic, method: isMethod } = value;
+    const { id, static: isStatic, method: isMethod, getId, setId } = value;
     if (loose) {
       initNodes.push(
         template.statement.ast`
@@ -39,7 +49,11 @@ export function buildPrivateNamesNodes(privateNamesMap, loose, state) {
         `,
       );
     } else if (isMethod && !isStatic) {
-      initNodes.push(template.statement.ast`var ${id} = new WeakSet();`);
+      if (getId || setId) {
+        initNodes.push(template.statement.ast`var ${id} = new WeakMap();`);
+      } else {
+        initNodes.push(template.statement.ast`var ${id} = new WeakSet();`);
+      }
     } else if (!isStatic) {
       initNodes.push(template.statement.ast`var ${id} = new WeakMap();`);
     }
@@ -121,6 +135,8 @@ const privateNameHandlerSpec = {
       static: isStatic,
       method: isMethod,
       methodId,
+      getId,
+      setId,
     } = privateNamesMap.get(name);
 
     if (isStatic && !isMethod) {
@@ -128,41 +144,57 @@ const privateNameHandlerSpec = {
         file.addHelper("classStaticPrivateFieldSpecGet"),
         [this.receiver(member), t.cloneNode(classRef), t.cloneNode(id)],
       );
-    } else if (isMethod) {
+    }
+    if (isMethod) {
+      if (getId || setId) {
+        return t.callExpression(file.addHelper("classPrivateFieldGet"), [
+          this.receiver(member),
+          t.cloneNode(id),
+        ]);
+      }
       return t.callExpression(file.addHelper("classPrivateMethodGet"), [
         this.receiver(member),
         t.cloneNode(id),
         t.cloneNode(methodId),
       ]);
-    } else {
-      return t.callExpression(file.addHelper("classPrivateFieldGet"), [
-        this.receiver(member),
-        t.cloneNode(id),
-      ]);
     }
+    return t.callExpression(file.addHelper("classPrivateFieldGet"), [
+      this.receiver(member),
+      t.cloneNode(id),
+    ]);
   },
 
   set(member, value) {
     const { classRef, privateNamesMap, file } = this;
     const { name } = member.node.property.id;
-    const { id, static: isStatic, method: isMethod } = privateNamesMap.get(
-      name,
-    );
+    const {
+      id,
+      static: isStatic,
+      method: isMethod,
+      setId,
+    } = privateNamesMap.get(name);
 
     if (isStatic && !isMethod) {
       return t.callExpression(
         file.addHelper("classStaticPrivateFieldSpecSet"),
         [this.receiver(member), t.cloneNode(classRef), t.cloneNode(id), value],
       );
-    } else if (isMethod) {
-      return t.callExpression(file.addHelper("classPrivateMethodSet"), []);
-    } else {
-      return t.callExpression(file.addHelper("classPrivateFieldSet"), [
-        this.receiver(member),
-        t.cloneNode(id),
-        value,
-      ]);
     }
+    if (isMethod) {
+      if (setId) {
+        return t.callExpression(file.addHelper("classPrivateFieldSet"), [
+          this.receiver(member),
+          t.cloneNode(id),
+          value,
+        ]);
+      }
+      return t.callExpression(file.addHelper("classPrivateMethodSet"), []);
+    }
+    return t.callExpression(file.addHelper("classPrivateFieldSet"), [
+      this.receiver(member),
+      t.cloneNode(id),
+      value,
+    ]);
   },
 
   call(member, args) {
@@ -255,21 +287,91 @@ function buildPrivateStaticFieldInitSpec(prop, privateNamesMap) {
 }
 
 function buildPrivateMethodInitLoose(ref, prop, privateNamesMap) {
-  const { methodId, id } = privateNamesMap.get(prop.node.key.id.name);
+  const privateName = privateNamesMap.get(prop.node.key.id.name);
+  const { methodId, id, getId, setId, initAdded } = privateName;
+  if (initAdded) return;
 
-  return template.statement.ast`
-    Object.defineProperty(${ref}, ${id}, {
-      // configurable is false by default
-      // enumerable is false by default
-      // writable is false by default
-      value: ${methodId.name}
+  if (methodId) {
+    return template.statement.ast`
+        Object.defineProperty(${ref}, ${id}, {
+          // configurable is false by default
+          // enumerable is false by default
+          // writable is false by default
+          value: ${methodId.name}
+        });
+      `;
+  }
+
+  if (getId || setId) {
+    privateNamesMap.set(prop.node.key.id.name, {
+      ...privateName,
+      initAdded: true,
     });
-  `;
+
+    if (getId && setId) {
+      return template.statement.ast`
+        Object.defineProperty(${ref}, ${id}, {
+          // configurable is false by default
+          // enumerable is false by default
+          // writable is false by default
+          get: ${getId.name},
+          set: ${setId.name}
+        });
+      `;
+    } else if (getId && !setId) {
+      return template.statement.ast`
+        Object.defineProperty(${ref}, ${id}, {
+          // configurable is false by default
+          // enumerable is false by default
+          // writable is false by default
+          get: ${getId.name}
+        });
+      `;
+    } else if (!getId && setId) {
+      return template.statement.ast`
+        Object.defineProperty(${ref}, ${id}, {
+          // configurable is false by default
+          // enumerable is false by default
+          // writable is false by default
+          set: ${setId.name}
+        });
+      `;
+    }
+  }
 }
 
 function buildPrivateInstanceMethodInitSpec(ref, prop, privateNamesMap) {
-  const { id } = privateNamesMap.get(prop.node.key.id.name);
+  const privateName = privateNamesMap.get(prop.node.key.id.name);
+  const { id, getId, setId, initAdded } = privateName;
+  if (initAdded) return;
 
+  if (getId || setId) {
+    privateNamesMap.set(prop.node.key.id.name, {
+      ...privateName,
+      initAdded: true,
+    });
+
+    if (getId && setId) {
+      return template.statement.ast`
+        ${id}.set(${ref}, {
+          get: ${getId.name},
+          set: ${setId.name}
+        });
+      `;
+    } else if (getId && !setId) {
+      return template.statement.ast`
+        ${id}.set(${ref}, {
+          get: ${getId.name}
+        });
+      `;
+    } else if (!getId && setId) {
+      return template.statement.ast`
+        ${id}.set(${ref}, {
+          set: ${setId.name}
+        });
+      `;
+    }
+  }
   return template.statement.ast`${id}.add(${ref})`;
 }
 
@@ -300,9 +402,43 @@ function buildPublicFieldInitSpec(ref, prop, state) {
 }
 
 function buildPrivateInstanceMethodDeclaration(prop, privateNamesMap) {
-  const { methodId } = privateNamesMap.get(prop.node.key.id.name);
-  const { params, body } = prop.node;
-  const methodValue = t.functionExpression(methodId, params, body);
+  const privateName = privateNamesMap.get(prop.node.key.id.name);
+  const {
+    methodId,
+    getId,
+    setId,
+    getterDeclared,
+    setterDeclared,
+  } = privateName;
+  const { params, body, generator, async } = prop.node;
+  const methodValue = t.functionExpression(
+    methodId,
+    params,
+    body,
+    generator,
+    async,
+  );
+  const isGetter = getId && !getterDeclared && params.length === 0;
+  const isSetter = setId && !setterDeclared && params.length > 0;
+
+  if (isGetter) {
+    privateNamesMap.set(prop.node.key.id.name, {
+      ...privateName,
+      getterDeclared: true,
+    });
+    return t.variableDeclaration("var", [
+      t.variableDeclarator(getId, methodValue),
+    ]);
+  }
+  if (isSetter) {
+    privateNamesMap.set(prop.node.key.id.name, {
+      ...privateName,
+      setterDeclared: true,
+    });
+    return t.variableDeclaration("var", [
+      t.variableDeclarator(setId, methodValue),
+    ]);
+  }
 
   return t.variableDeclaration("var", [
     t.variableDeclarator(methodId, methodValue),
@@ -318,37 +454,45 @@ export function buildFieldsInitNodes(
 ) {
   const staticNodes = [];
   const instanceNodes = [];
+  let needsClassRef = false;
 
   for (const prop of props) {
     const isStatic = prop.node.static;
-    const isPrivateField = prop.isClassPrivateProperty();
-    const isPrivateMethod = prop.isClassPrivateMethod();
+    const isInstance = !isStatic;
+    const isPrivate = prop.isPrivate();
+    const isPublic = !isPrivate;
+    const isField = prop.isProperty();
+    const isMethod = !isField;
 
     switch (true) {
-      case isStatic && isPrivateField && loose:
+      case isStatic && isPrivate && isField && loose:
+        needsClassRef = true;
         staticNodes.push(
           buildPrivateFieldInitLoose(t.cloneNode(ref), prop, privateNamesMap),
         );
         break;
-      case isStatic && isPrivateField && !loose:
+      case isStatic && isPrivate && isField && !loose:
+        needsClassRef = true;
         staticNodes.push(
           buildPrivateStaticFieldInitSpec(prop, privateNamesMap),
         );
         break;
-      case isStatic && !isPrivateField && loose:
+      case isStatic && isPublic && isField && loose:
+        needsClassRef = true;
         staticNodes.push(buildPublicFieldInitLoose(t.cloneNode(ref), prop));
         break;
-      case isStatic && !isPrivateField && !loose:
+      case isStatic && isPublic && isField && !loose:
+        needsClassRef = true;
         staticNodes.push(
           buildPublicFieldInitSpec(t.cloneNode(ref), prop, state),
         );
         break;
-      case !isStatic && isPrivateField && loose:
+      case isInstance && isPrivate && isField && loose:
         instanceNodes.push(
           buildPrivateFieldInitLoose(t.thisExpression(), prop, privateNamesMap),
         );
         break;
-      case !isStatic && isPrivateField && !loose:
+      case isInstance && isPrivate && isField && !loose:
         instanceNodes.push(
           buildPrivateInstanceFieldInitSpec(
             t.thisExpression(),
@@ -357,8 +501,8 @@ export function buildFieldsInitNodes(
           ),
         );
         break;
-      case !isStatic && isPrivateMethod && loose:
-        instanceNodes.push(
+      case isInstance && isPrivate && isMethod && loose:
+        instanceNodes.unshift(
           buildPrivateMethodInitLoose(
             t.thisExpression(),
             prop,
@@ -369,8 +513,8 @@ export function buildFieldsInitNodes(
           buildPrivateInstanceMethodDeclaration(prop, privateNamesMap),
         );
         break;
-      case !isStatic && isPrivateMethod && !loose:
-        instanceNodes.push(
+      case isInstance && isPrivate && isMethod && !loose:
+        instanceNodes.unshift(
           buildPrivateInstanceMethodInitSpec(
             t.thisExpression(),
             prop,
@@ -381,10 +525,10 @@ export function buildFieldsInitNodes(
           buildPrivateInstanceMethodDeclaration(prop, privateNamesMap),
         );
         break;
-      case !isStatic && !isPrivateField && loose:
+      case isInstance && isPublic && isField && loose:
         instanceNodes.push(buildPublicFieldInitLoose(t.thisExpression(), prop));
         break;
-      case !isStatic && !isPrivateField && !loose:
+      case isInstance && isPublic && isField && !loose:
         instanceNodes.push(
           buildPublicFieldInitSpec(t.thisExpression(), prop, state),
         );
@@ -394,5 +538,27 @@ export function buildFieldsInitNodes(
     }
   }
 
-  return { staticNodes, instanceNodes };
+  return {
+    staticNodes,
+    instanceNodes: instanceNodes.filter(Boolean),
+    wrapClass(path) {
+      for (const prop of props) {
+        prop.remove();
+      }
+
+      if (!needsClassRef) return path;
+
+      if (path.isClassExpression()) {
+        path.scope.push({ id: ref });
+        path.replaceWith(
+          t.assignmentExpression("=", t.cloneNode(ref), path.node),
+        );
+      } else if (!path.node.id) {
+        // Anonymous class declaration
+        path.node.id = ref;
+      }
+
+      return path;
+    },
+  };
 }

packages/babel-helper-create-class-features-plugin/src/index.js

@@ -1,11 +1,16 @@
 import nameFunction from "@babel/helper-function-name";
-import { types as t } from "@babel/core";
+import splitExportDeclaration from "@babel/helper-split-export-declaration";
 import {
   buildPrivateNamesNodes,
   buildPrivateNamesMap,
   transformPrivateNamesUsage,
   buildFieldsInitNodes,
 } from "./fields";
+import {
+  hasOwnDecorators,
+  buildDecoratedClass,
+  hasDecorators,
+} from "./decorators";
 import { injectInitialization, extractComputedKeys } from "./misc";
 import {
   enableFeature,
@@ -54,7 +59,9 @@ export function createClassFeaturePlugin({
         const loose = isLoose(this.file, FEATURES.fields);
 
         let constructor;
+        let isDecorated = hasOwnDecorators(path.node);
         const props = [];
+        const elements = [];
         const computedPaths = [];
         const privateNames = new Set();
         const body = path.get("body");
@@ -68,21 +75,54 @@ export function createClassFeaturePlugin({
 
           if (path.isPrivate()) {
             const { name } = path.node.key.id;
+            const getName = `get ${name}`;
+            const setName = `set ${name}`;
 
-            if (privateNames.has(name)) {
-              throw path.buildCodeFrameError("Duplicate private field");
+            if (path.node.kind === "get") {
+              if (
+                privateNames.has(getName) ||
+                (privateNames.has(name) && !privateNames.has(setName))
+              ) {
+                throw path.buildCodeFrameError("Duplicate private field");
+              }
+
+              privateNames.add(getName).add(name);
+            } else if (path.node.kind === "set") {
+              if (
+                privateNames.has(setName) ||
+                (privateNames.has(name) && !privateNames.has(getName))
+              ) {
+                throw path.buildCodeFrameError("Duplicate private field");
+              }
+
+              privateNames.add(setName).add(name);
+            } else {
+              if (
+                (privateNames.has(name) &&
+                  (!privateNames.has(getName) && !privateNames.has(setName))) ||
+                (privateNames.has(name) &&
+                  (privateNames.has(getName) || privateNames.has(setName)))
+              ) {
+                throw path.buildCodeFrameError("Duplicate private field");
+              }
+
+              privateNames.add(name);
             }
-            privateNames.add(name);
           }
 
-          if (path.isProperty() || path.isClassPrivateMethod()) {
-            props.push(path);
-          } else if (path.isClassMethod({ kind: "constructor" })) {
+          if (path.isClassMethod({ kind: "constructor" })) {
             constructor = path;
+          } else {
+            elements.push(path);
+            if (path.isProperty() || path.isPrivate()) {
+              props.push(path);
+            }
           }
+
+          if (!isDecorated) isDecorated = hasOwnDecorators(path.node);
         }
 
-        if (!props.length) return;
+        if (!props.length && !isDecorated) return;
 
         let ref;
 
@@ -93,13 +133,9 @@ export function createClassFeaturePlugin({
           ref = path.node.id;
         }
 
-        const keysNodes = extractComputedKeys(
-          ref,
-          path,
-          computedPaths,
-          this.file,
-        );
-
+        // NODE: These three functions don't support decorators yet,
+        //       but verifyUsedFeatures throws if there are both
+        //       decorators and private fields.
         const privateNamesMap = buildPrivateNamesMap(props);
         const privateNamesNodes = buildPrivateNamesNodes(
           privateNamesMap,
@@ -109,19 +145,34 @@ export function createClassFeaturePlugin({
 
         transformPrivateNamesUsage(ref, path, privateNamesMap, loose, state);
 
-        const { staticNodes, instanceNodes } = buildFieldsInitNodes(
-          ref,
-          props,
-          privateNamesMap,
-          state,
-          loose,
-        );
+        let keysNodes, staticNodes, instanceNodes, wrapClass;
+
+        if (isDecorated) {
+          staticNodes = keysNodes = [];
+          ({ instanceNodes, wrapClass } = buildDecoratedClass(
+            ref,
+            path,
+            elements,
+            this.file,
+          ));
+        } else {
+          keysNodes = extractComputedKeys(ref, path, computedPaths, this.file);
+          ({ staticNodes, instanceNodes, wrapClass } = buildFieldsInitNodes(
+            ref,
+            props,
+            privateNamesMap,
+            state,
+            loose,
+          ));
+        }
+
         if (instanceNodes.length > 0) {
           injectInitialization(
             path,
             constructor,
             instanceNodes,
             (referenceVisitor, state) => {
+              if (isDecorated) return;
               for (const prop of props) {
                 if (prop.node.static) continue;
                 prop.traverse(referenceVisitor, state);
@@ -130,28 +181,7 @@ export function createClassFeaturePlugin({
           );
         }
 
-        for (const prop of props) {
-          prop.remove();
-        }
-
-        if (
-          keysNodes.length === 0 &&
-          staticNodes.length === 0 &&
-          privateNamesNodes.length === 0
-        ) {
-          return;
-        }
-
-        if (path.isClassExpression()) {
-          path.scope.push({ id: ref });
-          path.replaceWith(
-            t.assignmentExpression("=", t.cloneNode(ref), path.node),
-          );
-        } else if (!path.node.id) {
-          // Anonymous class declaration
-          path.node.id = ref;
-        }
-
+        path = wrapClass(path);
         path.insertBefore(keysNodes);
         path.insertAfter([...privateNamesNodes, ...staticNodes]);
       },
@@ -161,6 +191,25 @@ export function createClassFeaturePlugin({
 
         throw path.buildCodeFrameError(`Unknown PrivateName "${path}"`);
       },
+
+      ExportDefaultDeclaration(path) {
+        if (this.file.get(versionKey) !== version) return;
+
+        const decl = path.get("declaration");
+
+        if (decl.isClassDeclaration() && hasDecorators(decl.node)) {
+          if (decl.node.id) {
+            // export default class Foo {}
+            //   -->
+            // class Foo {} export { Foo as default }
+            splitExportDeclaration(path);
+          } else {
+            // Annyms class declarations can be
+            // transformed as if they were expressions
+            decl.node.type = "ClassExpression";
+          }
+        }
+      },
     },
   };
 }

packages/babel-helper-create-class-features-plugin/test/fixtures/plugin-proposal-class-properties/recursive-class-property-type-challenge/input.js

@@ -0,0 +1,7 @@
+const sym = Symbol();
+const sym1 = Symbol();
+
+class A {
+  [sym]: A.B;
+  [sym1]: Array<A>;
+}

packages/babel-helper-create-class-features-plugin/test/fixtures/plugin-proposal-class-properties/recursive-class-property-type-challenge/options.json

@@ -0,0 +1,4 @@
+{
+  "presets": ["flow"],
+  "plugins": ["proposal-class-properties"]
+}

packages/babel-helper-create-class-features-plugin/test/fixtures/plugin-proposal-class-properties/recursive-class-property-type-challenge/output.js

@@ -0,0 +1,13 @@
+function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
+
+const sym = Symbol();
+const sym1 = Symbol();
+
+class A {
+  constructor() {
+    _defineProperty(this, sym, void 0);
+
+    _defineProperty(this, sym1, void 0);
+  }
+
+}

packages/babel-helper-create-class-features-plugin/test/fixtures/plugin-proposal-class-properties/recursive-class-property-type/input.js

@@ -0,0 +1,5 @@
+const sym = Symbol();
+
+class A {
+  [sym]: A;
+}

packages/babel-helper-create-class-features-plugin/test/fixtures/plugin-proposal-class-properties/recursive-class-property-type/options.json

@@ -0,0 +1,4 @@
+{
+  "presets": ["flow"],
+  "plugins": ["proposal-class-properties"]
+}

packages/babel-helper-create-class-features-plugin/test/fixtures/plugin-proposal-class-properties/recursive-class-property-type/output.js

@@ -0,0 +1,10 @@
+function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
+
+const sym = Symbol();
+
+class A {
+  constructor() {
+    _defineProperty(this, sym, void 0);
+  }
+
+}

packages/babel-helper-define-map/package.json

@@ -11,6 +11,6 @@
   "dependencies": {
     "@babel/helper-function-name": "^7.1.0",
     "@babel/types": "^7.0.0",
-    "lodash": "^4.17.10"
+    "lodash": "^4.17.11"
   }
 }

packages/babel-helper-fixtures/package.json

@@ -10,7 +10,7 @@
   "repository": "https://github.com/babel/babel/tree/master/packages/babel-helper-fixtures",
   "main": "lib/index.js",
   "dependencies": {
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "semver": "^5.3.0",
     "try-resolve": "^1.0.0"
   }

packages/babel-helper-module-transforms/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/helper-module-transforms",
-  "version": "7.1.0",
+  "version": "7.2.2",
   "description": "Babel helper functions for implementing ES6 module transformations",
   "author": "Logan Smyth <loganfsmyth@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -14,8 +14,8 @@
     "@babel/helper-module-imports": "^7.0.0",
     "@babel/helper-simple-access": "^7.1.0",
     "@babel/helper-split-export-declaration": "^7.0.0",
-    "@babel/template": "^7.1.0",
-    "@babel/types": "^7.0.0",
-    "lodash": "^4.17.10"
+    "@babel/template": "^7.2.2",
+    "@babel/types": "^7.2.2",
+    "lodash": "^4.17.11"
   }
 }

packages/babel-helper-module-transforms/src/normalize-and-load-metadata.js

@@ -8,6 +8,8 @@ export type ModuleMetadata = {
   // The name of the variable that will reference an object containing export names.
   exportNameListName: null | string,
 
+  hasExports: boolean,
+
   // Lookup from local binding to export information.
   local: Map<string, LocalExportMetadata>,
 
@@ -52,18 +54,7 @@ export type LocalExportMetadata = {
  * Check if the module has any exports that need handling.
  */
 export function hasExports(metadata: ModuleMetadata) {
-  const { local, source } = metadata;
-
-  return (
-    local.size > 0 ||
-    Array.from(source).some(([, meta]) => {
-      return (
-        meta.reexports.size > 0 ||
-        meta.reexportNamespace.size > 0 ||
-        !!meta.reexportAll
-      );
-    })
-  );
+  return metadata.hasExports;
 }
 
 /**
@@ -99,7 +90,10 @@ export default function normalizeModuleAndLoadMetadata(
 
   nameAnonymousExports(programPath);
 
-  const { local, source } = getModuleMetadata(programPath, { loose, lazy });
+  const { local, source, hasExports } = getModuleMetadata(programPath, {
+    loose,
+    lazy,
+  });
 
   removeModuleDeclarations(programPath);
 
@@ -127,6 +121,7 @@ export default function normalizeModuleAndLoadMetadata(
   return {
     exportName,
     exportNameListName: null,
+    hasExports,
     local,
     source,
   };
@@ -171,6 +166,7 @@ function getModuleMetadata(
     }
     return data;
   };
+  let hasExports = false;
   programPath.get("body").forEach(child => {
     if (child.isImportDeclaration()) {
       const data = getData(child.node.source);
@@ -219,6 +215,7 @@ function getModuleMetadata(
         }
       });
     } else if (child.isExportAllDeclaration()) {
+      hasExports = true;
       const data = getData(child.node.source);
       if (!data.loc) data.loc = child.node.loc;
 
@@ -226,6 +223,7 @@ function getModuleMetadata(
         loc: child.node.loc,
       };
     } else if (child.isExportNamedDeclaration() && child.node.source) {
+      hasExports = true;
       const data = getData(child.node.source);
       if (!data.loc) data.loc = child.node.loc;
 
@@ -242,6 +240,11 @@ function getModuleMetadata(
           throw exportName.buildCodeFrameError('Illegal export "__esModule".');
         }
       });
+    } else if (
+      child.isExportNamedDeclaration() ||
+      child.isExportDefaultDeclaration()
+    ) {
+      hasExports = true;
     }
   });
 
@@ -295,6 +298,7 @@ function getModuleMetadata(
   }
 
   return {
+    hasExports,
     local: localData,
     source: sourceData,
   };

packages/babel-helper-regex/package.json

@@ -9,6 +9,6 @@
   },
   "main": "lib/index.js",
   "dependencies": {
-    "lodash": "^4.17.10"
+    "lodash": "^4.17.11"
   }
 }

packages/babel-helper-replace-supers/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/helper-replace-supers",
-  "version": "7.1.0",
+  "version": "7.2.3",
   "description": "Helper function to replace supers",
   "repository": "https://github.com/babel/babel/tree/master/packages/babel-helper-replace-supers",
   "license": "MIT",
@@ -11,7 +11,7 @@
   "dependencies": {
     "@babel/helper-member-expression-to-functions": "^7.0.0",
     "@babel/helper-optimise-call-expression": "^7.0.0",
-    "@babel/traverse": "^7.1.0",
+    "@babel/traverse": "^7.2.3",
     "@babel/types": "^7.0.0"
   }
 }

packages/babel-helper-replace-supers/src/index.js

@@ -40,6 +40,9 @@ function skipAllButComputedKey(path) {
 }
 
 export const environmentVisitor = {
+  TypeAnnotation(path) {
+    path.skip();
+  },
   Function(path) {
     // Methods will be handled by the Method visit
     if (path.isMethod()) return;

packages/babel-helper-transform-fixture-test-runner/package.json

@@ -18,7 +18,7 @@
     "babel-check-duplicated-nodes": "^1.0.0",
     "jest": "^22.4.2",
     "jest-diff": "^22.4.0",
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "resolve": "^1.3.2",
     "source-map": "^0.5.0"
   }

packages/babel-helpers/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/helpers",
-  "version": "7.2.0",
+  "version": "7.3.1",
   "description": "Collection of helper functions used by Babel transforms.",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -13,7 +13,7 @@
   "dependencies": {
     "@babel/template": "^7.1.2",
     "@babel/traverse": "^7.1.5",
-    "@babel/types": "^7.2.0"
+    "@babel/types": "^7.3.0"
   },
   "devDependencies": {
     "@babel/helper-plugin-test-runner": "^7.0.0"

packages/babel-helpers/src/helpers.js

@@ -1048,7 +1048,11 @@ helpers.classPrivateFieldGet = helper("7.0.0-beta.0")`
     if (!privateMap.has(receiver)) {
       throw new TypeError("attempted to get private field on non-instance");
     }
-    return privateMap.get(receiver).value;
+    var descriptor = privateMap.get(receiver);
+    if (descriptor.get) {
+      return descriptor.get.call(receiver);
+    }
+    return descriptor.value;
   }
 `;
 
@@ -1058,13 +1062,19 @@ helpers.classPrivateFieldSet = helper("7.0.0-beta.0")`
       throw new TypeError("attempted to set private field on non-instance");
     }
     var descriptor = privateMap.get(receiver);
-    if (!descriptor.writable) {
-      // This should only throw in strict mode, but class bodies are
-      // always strict and private fields can only be used inside
-      // class bodies.
-      throw new TypeError("attempted to set read only private field");
+    if (descriptor.set) {
+      descriptor.set.call(receiver, value);
+    } else {
+      if (!descriptor.writable) {
+        // This should only throw in strict mode, but class bodies are
+        // always strict and private fields can only be used inside
+        // class bodies.
+        throw new TypeError("attempted to set read only private field");
+      }
+
+      descriptor.value = value;
     }
-    descriptor.value = value;
+
     return value;
   }
 `;
@@ -1213,23 +1223,430 @@ helpers.decorate = helper("7.1.5")`
 
   */
 
+  /*::
+
+  type Placements = {
+    static: Key[],
+    prototype: Key[],
+    own: Key[],
+  };
+
+  */
+
   // ClassDefinitionEvaluation (Steps 26-*)
   export default function _decorate(
     decorators /*: ClassDecorator[] */,
     factory /*: ClassFactory */,
     superClass /*: ?Class<*> */,
+    mixins /*: ?Array<Function> */,
   ) /*: Class<*> */ {
+    var api = _getDecoratorsApi();
+    if (mixins) {
+      for (var i = 0; i < mixins.length; i++) {
+        api = mixins[i](api);
+      }
+    }
+
     var r = factory(function initialize(O) {
-      _initializeInstanceElements(O, decorated.elements);
+      api.initializeInstanceElements(O, decorated.elements);
     }, superClass);
-    var decorated = _decorateClass(
+    var decorated = api.decorateClass(
       _coalesceClassElements(r.d.map(_createElementDescriptor)),
       decorators,
     );
 
-    _initializeClassElements(r.F, decorated.elements);
+    api.initializeClassElements(r.F, decorated.elements);
 
-    return _runClassFinishers(r.F, decorated.finishers);
+    return api.runClassFinishers(r.F, decorated.finishers);
+  }
+
+  function _getDecoratorsApi() {
+    _getDecoratorsApi = function() {
+      return api;
+    };
+
+    var api = {
+      elementsDefinitionOrder: [["method"], ["field"]],
+
+      // InitializeInstanceElements
+      initializeInstanceElements: function(
+        /*::<C>*/ O /*: C */,
+        elements /*: ElementDescriptor[] */,
+      ) {
+        ["method", "field"].forEach(function(kind) {
+          elements.forEach(function(element /*: ElementDescriptor */) {
+            if (element.kind === kind && element.placement === "own") {
+              this.defineClassElement(O, element);
+            }
+          }, this);
+        }, this);
+      },
+
+      // InitializeClassElements
+      initializeClassElements: function(
+        /*::<C>*/ F /*: Class<C> */,
+        elements /*: ElementDescriptor[] */,
+      ) {
+        var proto = F.prototype;
+
+        ["method", "field"].forEach(function(kind) {
+          elements.forEach(function(element /*: ElementDescriptor */) {
+            var placement = element.placement;
+            if (
+              element.kind === kind &&
+              (placement === "static" || placement === "prototype")
+            ) {
+              var receiver = placement === "static" ? F : proto;
+              this.defineClassElement(receiver, element);
+            }
+          }, this);
+        }, this);
+      },
+
+      // DefineClassElement
+      defineClassElement: function(
+        /*::<C>*/ receiver /*: C | Class<C> */,
+        element /*: ElementDescriptor */,
+      ) {
+        var descriptor /*: PropertyDescriptor */ = element.descriptor;
+        if (element.kind === "field") {
+          var initializer = element.initializer;
+          descriptor = {
+            enumerable: descriptor.enumerable,
+            writable: descriptor.writable,
+            configurable: descriptor.configurable,
+            value: initializer === void 0 ? void 0 : initializer.call(receiver),
+          };
+        }
+        Object.defineProperty(receiver, element.key, descriptor);
+      },
+
+      // DecorateClass
+      decorateClass: function(
+        elements /*: ElementDescriptor[] */,
+        decorators /*: ClassDecorator[] */,
+      ) /*: ElementsFinishers */ {
+        var newElements /*: ElementDescriptor[] */ = [];
+        var finishers /*: ClassFinisher[] */ = [];
+        var placements /*: Placements */ = {
+          static: [],
+          prototype: [],
+          own: [],
+        };
+
+        elements.forEach(function(element /*: ElementDescriptor */) {
+          this.addElementPlacement(element, placements);
+        }, this);
+
+        elements.forEach(function(element /*: ElementDescriptor */) {
+          if (!_hasDecorators(element)) return newElements.push(element);
+
+          var elementFinishersExtras /*: ElementFinishersExtras */ = this.decorateElement(
+            element,
+            placements,
+          );
+          newElements.push(elementFinishersExtras.element);
+          newElements.push.apply(newElements, elementFinishersExtras.extras);
+          finishers.push.apply(finishers, elementFinishersExtras.finishers);
+        }, this);
+
+        if (!decorators) {
+          return { elements: newElements, finishers: finishers };
+        }
+
+        var result /*: ElementsFinishers */ = this.decorateConstructor(
+          newElements,
+          decorators,
+        );
+        finishers.push.apply(finishers, result.finishers);
+        result.finishers = finishers;
+
+        return result;
+      },
+
+      // AddElementPlacement
+      addElementPlacement: function(
+        element /*: ElementDescriptor */,
+        placements /*: Placements */,
+        silent /*: boolean */,
+      ) {
+        var keys = placements[element.placement];
+        if (!silent && keys.indexOf(element.key) !== -1) {
+          throw new TypeError("Duplicated element (" + element.key + ")");
+        }
+        keys.push(element.key);
+      },
+
+      // DecorateElement
+      decorateElement: function(
+        element /*: ElementDescriptor */,
+        placements /*: Placements */,
+      ) /*: ElementFinishersExtras */ {
+        var extras /*: ElementDescriptor[] */ = [];
+        var finishers /*: ClassFinisher[] */ = [];
+
+        for (
+          var decorators = element.decorators, i = decorators.length - 1;
+          i >= 0;
+          i--
+        ) {
+          // (inlined) RemoveElementPlacement
+          var keys = placements[element.placement];
+          keys.splice(keys.indexOf(element.key), 1);
+
+          var elementObject /*: ElementObjectInput */ = this.fromElementDescriptor(
+            element,
+          );
+          var elementFinisherExtras /*: ElementFinisherExtras */ = this.toElementFinisherExtras(
+            (0, decorators[i])(elementObject) /*: ElementObjectOutput */ ||
+              elementObject,
+          );
+
+          element = elementFinisherExtras.element;
+          this.addElementPlacement(element, placements);
+
+          if (elementFinisherExtras.finisher) {
+            finishers.push(elementFinisherExtras.finisher);
+          }
+
+          var newExtras /*: ElementDescriptor[] | void */ =
+            elementFinisherExtras.extras;
+          if (newExtras) {
+            for (var j = 0; j < newExtras.length; j++) {
+              this.addElementPlacement(newExtras[j], placements);
+            }
+            extras.push.apply(extras, newExtras);
+          }
+        }
+
+        return { element: element, finishers: finishers, extras: extras };
+      },
+
+      // DecorateConstructor
+      decorateConstructor: function(
+        elements /*: ElementDescriptor[] */,
+        decorators /*: ClassDecorator[] */,
+      ) /*: ElementsFinishers */ {
+        var finishers /*: ClassFinisher[] */ = [];
+
+        for (var i = decorators.length - 1; i >= 0; i--) {
+          var obj /*: ClassObject */ = this.fromClassDescriptor(elements);
+          var elementsAndFinisher /*: ElementsFinisher */ = this.toClassDescriptor(
+            (0, decorators[i])(obj) /*: ClassObject */ || obj,
+          );
+
+          if (elementsAndFinisher.finisher !== undefined) {
+            finishers.push(elementsAndFinisher.finisher);
+          }
+
+          if (elementsAndFinisher.elements !== undefined) {
+            elements = elementsAndFinisher.elements;
+
+            for (var j = 0; j < elements.length - 1; j++) {
+              for (var k = j + 1; k < elements.length; k++) {
+                if (
+                  elements[j].key === elements[k].key &&
+                  elements[j].placement === elements[k].placement
+                ) {
+                  throw new TypeError(
+                    "Duplicated element (" + elements[j].key + ")",
+                  );
+                }
+              }
+            }
+          }
+        }
+
+        return { elements: elements, finishers: finishers };
+      },
+
+      // FromElementDescriptor
+      fromElementDescriptor: function(
+        element /*: ElementDescriptor */,
+      ) /*: ElementObject */ {
+        var obj /*: ElementObject */ = {
+          kind: element.kind,
+          key: element.key,
+          placement: element.placement,
+          descriptor: element.descriptor,
+        };
+
+        var desc = {
+          value: "Descriptor",
+          configurable: true,
+        };
+        Object.defineProperty(obj, Symbol.toStringTag, desc);
+
+        if (element.kind === "field") obj.initializer = element.initializer;
+
+        return obj;
+      },
+
+      // ToElementDescriptors
+      toElementDescriptors: function(
+        elementObjects /*: ElementObject[] */,
+      ) /*: ElementDescriptor[] */ {
+        if (elementObjects === undefined) return;
+        return toArray(elementObjects).map(function(elementObject) {
+          var element = this.toElementDescriptor(elementObject);
+          this.disallowProperty(elementObject, "finisher", "An element descriptor");
+          this.disallowProperty(elementObject, "extras", "An element descriptor");
+          return element;
+        }, this);
+      },
+
+      // ToElementDescriptor
+      toElementDescriptor: function(
+        elementObject /*: ElementObject */,
+      ) /*: ElementDescriptor */ {
+        var kind = String(elementObject.kind);
+        if (kind !== "method" && kind !== "field") {
+          throw new TypeError(
+            'An element descriptor\\'s .kind property must be either "method" or' +
+              ' "field", but a decorator created an element descriptor with' +
+              ' .kind "' +
+              kind +
+              '"',
+          );
+        }
+
+        var key = toPropertyKey(elementObject.key);
+
+        var placement = String(elementObject.placement);
+        if (
+          placement !== "static" &&
+          placement !== "prototype" &&
+          placement !== "own"
+        ) {
+          throw new TypeError(
+            'An element descriptor\\'s .placement property must be one of "static",' +
+              ' "prototype" or "own", but a decorator created an element descriptor' +
+              ' with .placement "' +
+              placement +
+              '"',
+          );
+        }
+
+        var descriptor /*: PropertyDescriptor */ = elementObject.descriptor;
+
+        this.disallowProperty(elementObject, "elements", "An element descriptor");
+
+        var element /*: ElementDescriptor */ = {
+          kind: kind,
+          key: key,
+          placement: placement,
+          descriptor: Object.assign({}, descriptor),
+        };
+
+        if (kind !== "field") {
+          this.disallowProperty(elementObject, "initializer", "A method descriptor");
+        } else {
+          this.disallowProperty(
+            descriptor,
+            "get",
+            "The property descriptor of a field descriptor",
+          );
+          this.disallowProperty(
+            descriptor,
+            "set",
+            "The property descriptor of a field descriptor",
+          );
+          this.disallowProperty(
+            descriptor,
+            "value",
+            "The property descriptor of a field descriptor",
+          );
+
+          element.initializer = elementObject.initializer;
+        }
+
+        return element;
+      },
+
+      toElementFinisherExtras: function(
+        elementObject /*: ElementObject */,
+      ) /*: ElementFinisherExtras */ {
+        var element /*: ElementDescriptor */ = this.toElementDescriptor(
+          elementObject,
+        );
+        var finisher /*: ClassFinisher */ = _optionalCallableProperty(
+          elementObject,
+          "finisher",
+        );
+        var extras /*: ElementDescriptors[] */ = this.toElementDescriptors(
+          elementObject.extras,
+        );
+
+        return { element: element, finisher: finisher, extras: extras };
+      },
+
+      // FromClassDescriptor
+      fromClassDescriptor: function(
+        elements /*: ElementDescriptor[] */,
+      ) /*: ClassObject */ {
+        var obj = {
+          kind: "class",
+          elements: elements.map(this.fromElementDescriptor, this),
+        };
+
+        var desc = { value: "Descriptor", configurable: true };
+        Object.defineProperty(obj, Symbol.toStringTag, desc);
+
+        return obj;
+      },
+
+      // ToClassDescriptor
+      toClassDescriptor: function(
+        obj /*: ClassObject */,
+      ) /*: ElementsFinisher */ {
+        var kind = String(obj.kind);
+        if (kind !== "class") {
+          throw new TypeError(
+            'A class descriptor\\'s .kind property must be "class", but a decorator' +
+              ' created a class descriptor with .kind "' +
+              kind +
+              '"',
+          );
+        }
+
+        this.disallowProperty(obj, "key", "A class descriptor");
+        this.disallowProperty(obj, "placement", "A class descriptor");
+        this.disallowProperty(obj, "descriptor", "A class descriptor");
+        this.disallowProperty(obj, "initializer", "A class descriptor");
+        this.disallowProperty(obj, "extras", "A class descriptor");
+
+        var finisher = _optionalCallableProperty(obj, "finisher");
+        var elements = this.toElementDescriptors(obj.elements);
+
+        return { elements: elements, finisher: finisher };
+      },
+
+      // RunClassFinishers
+      runClassFinishers: function(
+        constructor /*: Class<*> */,
+        finishers /*: ClassFinisher[] */,
+      ) /*: Class<*> */ {
+        for (var i = 0; i < finishers.length; i++) {
+          var newConstructor /*: ?Class<*> */ = (0, finishers[i])(constructor);
+          if (newConstructor !== undefined) {
+            // NOTE: This should check if IsConstructor(newConstructor) is false.
+            if (typeof newConstructor !== "function") {
+              throw new TypeError("Finishers must return a constructor.");
+            }
+            constructor = newConstructor;
+          }
+        }
+        return constructor;
+      },
+
+      disallowProperty: function(obj, name, objectType) {
+        if (obj[name] !== undefined) {
+          throw new TypeError(objectType + " can't have a ." + name + " property.");
+        }
+      }
+    };
+
+    return api;
   }
 
   // ClassElementEvaluation
@@ -1246,10 +1663,6 @@ helpers.decorate = helper("7.1.5")`
         configurable: true,
         enumerable: false,
       };
-      Object.defineProperty(def.value, "name", {
-        value: typeof key === "symbol" ? "" : key,
-        configurable: true,
-      });
     } else if (def.kind === "get") {
       descriptor = { get: def.value, configurable: true, enumerable: false };
     } else if (def.kind === "set") {
@@ -1264,8 +1677,8 @@ helpers.decorate = helper("7.1.5")`
       placement: def.static
         ? "static"
         : def.kind === "field"
-          ? "own"
-          : "prototype",
+        ? "own"
+        : "prototype",
       descriptor: descriptor,
     };
     if (def.decorators) element.decorators = def.decorators;
@@ -1292,7 +1705,9 @@ helpers.decorate = helper("7.1.5")`
   ) /*: ElementDescriptor[] */ {
     var newElements /*: ElementDescriptor[] */ = [];
 
-    var isSameElement = function(other /*: ElementDescriptor */) /*: boolean */ {
+    var isSameElement = function(
+      other /*: ElementDescriptor */,
+    ) /*: boolean */ {
       return (
         other.kind === "method" &&
         other.key === element.key &&
@@ -1351,365 +1766,6 @@ helpers.decorate = helper("7.1.5")`
     );
   }
 
-  // InitializeClassElements
-  function _initializeClassElements /*::<C>*/(
-    F /*: Class<C> */,
-    elements /*: ElementDescriptor[] */,
-  ) {
-    var proto = F.prototype;
-
-    ["method", "field"].forEach(function(kind) {
-      elements.forEach(function(element /*: ElementDescriptor */) {
-        var placement = element.placement;
-        if (
-          element.kind === kind &&
-          (placement === "static" || placement === "prototype")
-        ) {
-          var receiver = placement === "static" ? F : proto;
-          _defineClassElement(receiver, element);
-        }
-      });
-    });
-  }
-
-  // InitializeInstanceElements
-  function _initializeInstanceElements /*::<C>*/(
-    O /*: C */,
-    elements /*: ElementDescriptor[] */,
-  ) {
-    ["method", "field"].forEach(function(kind) {
-      elements.forEach(function(element /*: ElementDescriptor */) {
-        if (element.kind === kind && element.placement === "own") {
-          _defineClassElement(O, element);
-        }
-      });
-    });
-  }
-
-  // DefineClassElement
-  function _defineClassElement /*::<C>*/(
-    receiver /*: C | Class<C> */,
-    element /*: ElementDescriptor */,
-  ) {
-    var descriptor /*: PropertyDescriptor */ = element.descriptor;
-    if (element.kind === "field") {
-      var initializer = element.initializer;
-      descriptor = {
-        enumerable: descriptor.enumerable,
-        writable: descriptor.writable,
-        configurable: descriptor.configurable,
-        value: initializer === void 0 ? void 0 : initializer.call(receiver),
-      };
-    }
-    Object.defineProperty(receiver, element.key, descriptor);
-  }
-
-  /*::
-
-  type Placements = {
-    static: Key[],
-    prototype: Key[],
-    own: Key[],
-  };
-
-  */
-
-  // DecorateClass
-  function _decorateClass(
-    elements /*: ElementDescriptor[] */,
-    decorators /*: ClassDecorator[] */,
-  ) /*: ElementsFinishers */ {
-    var newElements /*: ElementDescriptor[] */ = [];
-    var finishers /*: ClassFinisher[] */ = [];
-    var placements /*: Placements */ = { static: [], prototype: [], own: [] };
-
-    elements.forEach(function(element /*: ElementDescriptor */) {
-      _addElementPlacement(element, placements);
-    });
-
-    elements.forEach(function(element /*: ElementDescriptor */) {
-      if (!_hasDecorators(element)) return newElements.push(element);
-
-      var elementFinishersExtras /*: ElementFinishersExtras */ = _decorateElement(
-        element,
-        placements,
-      );
-      newElements.push(elementFinishersExtras.element);
-      newElements.push.apply(newElements, elementFinishersExtras.extras);
-      finishers.push.apply(finishers, elementFinishersExtras.finishers);
-    });
-
-    if (!decorators) {
-      return { elements: newElements, finishers: finishers };
-    }
-
-    var result /*: ElementsFinishers */ = _decorateConstructor(
-      newElements,
-      decorators,
-    );
-    finishers.push.apply(finishers, result.finishers);
-    result.finishers = finishers;
-
-    return result;
-  }
-
-  // AddElementPlacement
-  function _addElementPlacement(
-    element /*: ElementDescriptor */,
-    placements /*: Placements */,
-    silent /*: boolean */,
-  ) {
-    var keys = placements[element.placement];
-    if (!silent && keys.indexOf(element.key) !== -1) {
-      throw new TypeError("Duplicated element (" + element.key + ")");
-    }
-    keys.push(element.key);
-  }
-
-  // DecorateElement
-  function _decorateElement(
-    element /*: ElementDescriptor */,
-    placements /*: Placements */,
-  ) /*: ElementFinishersExtras */ {
-    var extras /*: ElementDescriptor[] */ = [];
-    var finishers /*: ClassFinisher[] */ = [];
-
-    for (
-      var decorators = element.decorators, i = decorators.length - 1;
-      i >= 0;
-      i--
-    ) {
-      // (inlined) RemoveElementPlacement
-      var keys = placements[element.placement];
-      keys.splice(keys.indexOf(element.key), 1);
-
-      var elementObject /*: ElementObjectInput */ = _fromElementDescriptor(
-        element,
-      );
-      var elementFinisherExtras /*: ElementFinisherExtras */ = _toElementFinisherExtras(
-        (0, decorators[i])(elementObject) /*: ElementObjectOutput */ ||
-          elementObject,
-      );
-
-      element = elementFinisherExtras.element;
-      _addElementPlacement(element, placements);
-
-      if (elementFinisherExtras.finisher) {
-        finishers.push(elementFinisherExtras.finisher);
-      }
-
-      var newExtras /*: ElementDescriptor[] | void */ =
-        elementFinisherExtras.extras;
-      if (newExtras) {
-        for (var j = 0; j < newExtras.length; j++) {
-          _addElementPlacement(newExtras[j], placements);
-        }
-        extras.push.apply(extras, newExtras);
-      }
-    }
-
-    return { element: element, finishers: finishers, extras: extras };
-  }
-
-  // DecorateConstructor
-  function _decorateConstructor(
-    elements /*: ElementDescriptor[] */,
-    decorators /*: ClassDecorator[] */,
-  ) /*: ElementsFinishers */ {
-    var finishers /*: ClassFinisher[] */ = [];
-
-    for (var i = decorators.length - 1; i >= 0; i--) {
-      var obj /*: ClassObject */ = _fromClassDescriptor(elements);
-      var elementsAndFinisher /*: ElementsFinisher */ = _toClassDescriptor(
-        (0, decorators[i])(obj) /*: ClassObject */ || obj,
-      );
-
-      if (elementsAndFinisher.finisher !== undefined) {
-        finishers.push(elementsAndFinisher.finisher);
-      }
-
-      if (elementsAndFinisher.elements !== undefined) {
-        elements = elementsAndFinisher.elements;
-
-        for (var j = 0; j < elements.length - 1; j++) {
-          for (var k = j + 1; k < elements.length; k++) {
-            if (
-              elements[j].key === elements[k].key &&
-              elements[j].placement === elements[k].placement
-            ) {
-              throw new TypeError("Duplicated element (" + elements[j].key + ")");
-            }
-          }
-        }
-      }
-    }
-
-    return { elements: elements, finishers: finishers };
-  }
-
-  // FromElementDescriptor
-  function _fromElementDescriptor(
-    element /*: ElementDescriptor */,
-  ) /*: ElementObject */ {
-    var obj /*: ElementObject */ = {
-      kind: element.kind,
-      key: element.key,
-      placement: element.placement,
-      descriptor: element.descriptor,
-    };
-
-    var desc = {
-      value: "Descriptor",
-      configurable: true,
-    };
-    Object.defineProperty(obj, Symbol.toStringTag, desc);
-
-    if (element.kind === "field") obj.initializer = element.initializer;
-
-    return obj;
-  }
-
-  // ToElementDescriptors
-  function _toElementDescriptors(
-    elementObjects /*: ElementObject[] */,
-  ) /*: ElementDescriptor[] */ {
-    if (elementObjects === undefined) return;
-    return toArray(elementObjects).map(function(elementObject) {
-      var element = _toElementDescriptor(elementObject);
-      _disallowProperty(elementObject, "finisher", "An element descriptor");
-      _disallowProperty(elementObject, "extras", "An element descriptor");
-      return element;
-    });
-  }
-
-  // ToElementDescriptor
-  function _toElementDescriptor(
-    elementObject /*: ElementObject */,
-  ) /*: ElementDescriptor */ {
-    var kind = String(elementObject.kind);
-    if (kind !== "method" && kind !== "field") {
-      throw new TypeError(
-        'An element descriptor\\'s .kind property must be either "method" or' +
-          ' "field", but a decorator created an element descriptor with' +
-          ' .kind "' +
-          kind +
-          '"',
-      );
-    }
-
-    var key = toPropertyKey(elementObject.key);
-
-    var placement = String(elementObject.placement);
-    if (
-      placement !== "static" &&
-      placement !== "prototype" &&
-      placement !== "own"
-    ) {
-      throw new TypeError(
-        'An element descriptor\\'s .placement property must be one of "static",' +
-          ' "prototype" or "own", but a decorator created an element descriptor' +
-          ' with .placement "' +
-          placement +
-          '"',
-      );
-    }
-
-    var descriptor /*: PropertyDescriptor */ = elementObject.descriptor;
-
-    _disallowProperty(elementObject, "elements", "An element descriptor");
-
-    var element /*: ElementDescriptor */ = {
-      kind: kind,
-      key: key,
-      placement: placement,
-      descriptor: Object.assign({}, descriptor),
-    };
-
-    if (kind !== "field") {
-      _disallowProperty(elementObject, "initializer", "A method descriptor");
-    } else {
-      _disallowProperty(
-        descriptor,
-        "get",
-        "The property descriptor of a field descriptor",
-      );
-      _disallowProperty(
-        descriptor,
-        "set",
-        "The property descriptor of a field descriptor",
-      );
-      _disallowProperty(
-        descriptor,
-        "value",
-        "The property descriptor of a field descriptor",
-      );
-
-      element.initializer = elementObject.initializer;
-    }
-
-    return element;
-  }
-
-  function _toElementFinisherExtras(
-    elementObject /*: ElementObject */,
-  ) /*: ElementFinisherExtras */ {
-    var element /*: ElementDescriptor */ = _toElementDescriptor(elementObject);
-    var finisher /*: ClassFinisher */ = _optionalCallableProperty(
-      elementObject,
-      "finisher",
-    );
-    var extras /*: ElementDescriptors[] */ = _toElementDescriptors(
-      elementObject.extras,
-    );
-
-    return { element: element, finisher: finisher, extras: extras };
-  }
-
-  // FromClassDescriptor
-  function _fromClassDescriptor(
-    elements /*: ElementDescriptor[] */,
-  ) /*: ClassObject */ {
-    var obj = {
-      kind: "class",
-      elements: elements.map(_fromElementDescriptor),
-    };
-
-    var desc = { value: "Descriptor", configurable: true };
-    Object.defineProperty(obj, Symbol.toStringTag, desc);
-
-    return obj;
-  }
-
-  // ToClassDescriptor
-  function _toClassDescriptor(obj /*: ClassObject */) /*: ElementsFinisher */ {
-    var kind = String(obj.kind);
-    if (kind !== "class") {
-      throw new TypeError(
-        'A class descriptor\\'s .kind property must be "class", but a decorator' +
-          ' created a class descriptor with .kind "' +
-          kind +
-          '"',
-      );
-    }
-
-    _disallowProperty(obj, "key", "A class descriptor");
-    _disallowProperty(obj, "placement", "A class descriptor");
-    _disallowProperty(obj, "descriptor", "A class descriptor");
-    _disallowProperty(obj, "initializer", "A class descriptor");
-    _disallowProperty(obj, "extras", "A class descriptor");
-
-    var finisher = _optionalCallableProperty(obj, "finisher");
-    var elements = _toElementDescriptors(obj.elements);
-
-    return { elements: elements, finisher: finisher };
-  }
-
-  function _disallowProperty(obj, name, objectType) {
-    if (obj[name] !== undefined) {
-      throw new TypeError(objectType + " can't have a ." + name + " property.");
-    }
-  }
-
   function _optionalCallableProperty /*::<T>*/(
     obj /*: T */,
     name /*: $Keys<T> */,
@@ -1721,23 +1777,6 @@ helpers.decorate = helper("7.1.5")`
     return value;
   }
 
-  // RunClassFinishers
-  function _runClassFinishers(
-    constructor /*: Class<*> */,
-    finishers /*: ClassFinisher[] */,
-  ) /*: Class<*> */ {
-    for (var i = 0; i < finishers.length; i++) {
-      var newConstructor /*: ?Class<*> */ = (0, finishers[i])(constructor);
-      if (newConstructor !== undefined) {
-        // NOTE: This should check if IsConstructor(newConstructor) is false.
-        if (typeof newConstructor !== "function") {
-          throw new TypeError("Finishers must return a constructor.");
-        }
-        constructor = newConstructor;
-      }
-    }
-    return constructor;
-  }
 `;
 
 helpers.classPrivateMethodGet = helper("7.1.6")`
@@ -1754,3 +1793,75 @@ helpers.classPrivateMethodSet = helper("7.1.6")`
     throw new TypeError("attempted to reassign private method");
   }
 `;
+
+helpers.wrapRegExp = helper("7.2.6")`
+  import wrapNativeSuper from "wrapNativeSuper";
+  import getPrototypeOf from "getPrototypeOf";
+  import possibleConstructorReturn from "possibleConstructorReturn";
+  import inherits from "inherits";
+
+  export default function _wrapRegExp(re, groups) {
+    _wrapRegExp = function(re, groups) {
+      return new BabelRegExp(re, groups);
+    };
+
+    var _RegExp = wrapNativeSuper(RegExp);
+    var _super = RegExp.prototype;
+    var _groups = new WeakMap();
+
+    function BabelRegExp(re, groups) {
+      var _this = _RegExp.call(this, re);
+      _groups.set(_this, groups);
+      return _this;
+    }
+    inherits(BabelRegExp, _RegExp);
+
+    BabelRegExp.prototype.exec = function(str) {
+      var result = _super.exec.call(this, str);
+      if (result) result.groups = buildGroups(result, this);
+      return result;
+    };
+    BabelRegExp.prototype[Symbol.replace] = function(str, substitution) {
+      if (typeof substitution === "string") {
+        var groups = _groups.get(this);
+        return _super[Symbol.replace].call(
+          this,
+          str,
+          substitution.replace(/\\$<([^>]+)>/g, function(_, name) {
+            return "$" + groups[name];
+          })
+        );
+      } else if (typeof substitution === "function") {
+        var _this = this;
+        return _super[Symbol.replace].call(
+          this,
+          str,
+          function() {
+            var args = [];
+            args.push.apply(args, arguments);
+            if (typeof args[args.length - 1] !== "object") {
+              // Modern engines already pass result.groups as the last arg.
+              args.push(buildGroups(args, _this));
+            }
+            return substitution.apply(this, args);
+          }
+        );
+      } else {
+        return _super[Symbol.replace].call(this, str, substitution);
+      }
+    }
+
+    function buildGroups(result, re) {
+      // NOTE: This function should return undefined if there are no groups,
+      // but in that case Babel doesn't add the wrapper anyway.
+
+      var g = _groups.get(re);
+      return Object.keys(groups).reduce(function(groups, name) {
+        groups[name] = result[g[name]];
+        return groups;
+      }, Object.create(null));
+    }
+
+    return _wrapRegExp.apply(this, arguments);
+  }
+`;

packages/babel-node/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/node",
-  "version": "7.2.0",
+  "version": "7.2.2",
   "description": "Babel command line",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -22,14 +22,14 @@
     "@babel/polyfill": "^7.0.0",
     "@babel/register": "^7.0.0",
     "commander": "^2.8.1",
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "v8flags": "^3.1.1"
   },
   "peerDependencies": {
     "@babel/core": "^7.0.0-0"
   },
   "devDependencies": {
-    "@babel/core": "^7.2.0",
+    "@babel/core": "^7.2.2",
     "@babel/helper-fixtures": "^7.2.0",
     "fs-readdir-recursive": "^1.0.0",
     "output-file-sync": "^2.0.0"

packages/babel-node/src/_babel-node.js

@@ -52,7 +52,7 @@ program.option(
   "The name of the 'env' to use when loading configs and plugins. " +
     "Defaults to the value of BABEL_ENV, or else NODE_ENV, or else 'development'.",
 );
-commander.option(
+program.option(
   "--root-mode [mode]",
   "The project-root resolution mode. " +
     "One of 'root' (the default), 'upward', or 'upward-optional'.",

packages/babel-node/test/fixtures/babel-node/node_--inspect/options.json

@@ -0,0 +1,6 @@
+{
+  "args": ["--inspect", "--eval", "console.log('foo');"],
+  "stderr": "Debugger listening on",
+  "stderrContains": true,
+  "stdout": "foo"
+}

packages/babel-node/test/fixtures/babel-node/node_--no-lazy/options.json

@@ -0,0 +1,4 @@
+{
+  "args": ["--nolazy", "--eval", "console.log('foo')"],
+  "stdout": "foo"
+}

packages/babel-node/test/fixtures/babel-node/node_-gc_alias_--expose-gc/options.json

@@ -0,0 +1,4 @@
+{
+  "args": ["-gc", "--eval", "console.log(typeof global.gc)"],
+  "stdout": "function"
+}

packages/babel-parser/README.md

@@ -2,7 +2,7 @@
 
 > A JavaScript parser
 
-See our website [@babel/parser](https://babeljs.io/docs/en/next/babel-parser.html) for more information or the [issues](https://github.com/babel/babel/issues?utf8=%E2%9C%93&q=is%3Aissue+label%3A%22pkg%3A%20babylon%22+is%3Aopen) associated with this package.
+See our website [@babel/parser](https://babeljs.io/docs/en/next/babel-parser.html) for more information or the [issues](https://github.com/babel/babel/issues?utf8=%E2%9C%93&q=is%3Aissue+label%3A%22pkg%3A+parser+%28babylon%29%22+is%3Aopen) associated with this package.
 
 ## Install
 

packages/babel-parser/ast/spec.md

@@ -1149,6 +1149,7 @@ A specifier in an import or export declaration.
 ```js
 interface ImportDeclaration <: ModuleDeclaration {
   type: "ImportDeclaration";
+  importKind: null | "type" | "typeof" | "value";
   specifiers: [ ImportSpecifier | ImportDefaultSpecifier | ImportNamespaceSpecifier ];
   source: Literal;
 }
@@ -1156,6 +1157,8 @@ interface ImportDeclaration <: ModuleDeclaration {
 
 An import declaration, e.g., `import foo from "mod";`.
 
+> importKind is only set when `flow` plugin enabled in babel-parser
+
 ### ImportSpecifier
 
 ```js

packages/babel-parser/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@babel/parser",
-  "version": "7.2.0",
+  "version": "7.3.3",
   "description": "A JavaScript parser",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
@@ -28,9 +28,10 @@
     "node": ">=6.0.0"
   },
   "devDependencies": {
+    "@babel/code-frame": "^7.0.0",
     "@babel/helper-fixtures": "^7.2.0",
     "charcodes": "0.1.0",
-    "unicode-11.0.0": "^0.7.7"
+    "unicode-11.0.0": "^0.7.8"
   },
   "bin": {
     "parser": "./bin/babel-parser.js"

packages/babel-parser/scripts/generate-identifier-regex.js

@@ -60,11 +60,15 @@ function generate(chars) {
 const startData = generate(start);
 const contData = generate(cont);
 
+console.log("/* prettier-ignore */");
 console.log('let nonASCIIidentifierStartChars = "' + startData.nonASCII + '";');
+console.log("/* prettier-ignore */");
 console.log('let nonASCIIidentifierChars = "' + contData.nonASCII + '";');
+console.log("/* prettier-ignore */");
 console.log(
   "const astralIdentifierStartCodes = " + JSON.stringify(startData.astral) + ";"
 );
+console.log("/* prettier-ignore */");
 console.log(
   "const astralIdentifierCodes = " + JSON.stringify(contData.astral) + ";"
 );

packages/babel-parser/src/parser/base.js

@@ -1,8 +1,6 @@
 // @flow
 
 import type { Options } from "../options";
-import { reservedWords } from "../util/identifier";
-
 import type State from "../tokenizer/state";
 import type { PluginsMap } from "./index";
 
@@ -16,21 +14,13 @@ export default class BaseParser {
 
   // Initialized by Tokenizer
   state: State;
-  input: string;
-
-  isReservedWord(word: string): boolean {
-    if (word === "await") {
-      return this.inModule;
-    } else {
-      return reservedWords[6](word);
-    }
-  }
 
   hasPlugin(name: string): boolean {
-    return Object.hasOwnProperty.call(this.plugins, name);
+    return this.plugins.has(name);
   }
 
   getPluginOption(plugin: string, name: string) {
-    if (this.hasPlugin(plugin)) return this.plugins[plugin][name];
+    // $FlowIssue
+    if (this.hasPlugin(plugin)) return this.plugins.get(plugin)[name];
   }
 }

packages/babel-parser/src/parser/expression.js

@@ -21,7 +21,12 @@
 import { types as tt, type TokenType } from "../tokenizer/types";
 import * as N from "../types";
 import LValParser from "./lval";
-import { reservedWords } from "../util/identifier";
+import {
+  isKeyword,
+  isReservedWord,
+  isStrictReservedWord,
+  isStrictBindReservedWord,
+} from "../util/identifier";
 import type { Pos, Position } from "../util/location";
 import * as charCodes from "charcodes";
 
@@ -122,14 +127,23 @@ export default class ExpressionParser extends LValParser {
   ): N.Expression {
     const startPos = this.state.start;
     const startLoc = this.state.startLoc;
-    if (this.match(tt._yield) && this.state.inGenerator) {
-      let left = this.parseYield();
-      if (afterLeftParse) {
-        left = afterLeftParse.call(this, left, startPos, startLoc);
+    if (this.isContextual("yield")) {
+      if (this.state.inGenerator) {
+        let left = this.parseYield(noIn);
+        if (afterLeftParse) {
+          left = afterLeftParse.call(this, left, startPos, startLoc);
+        }
+        return left;
+      } else {
+        // The tokenizer will assume an expression is allowed after
+        // `yield`, but this isn't that kind of yield
+        this.state.exprAllowed = false;
       }
-      return left;
     }
 
+    const oldCommaAfterSpreadAt = this.state.commaAfterSpreadAt;
+    this.state.commaAfterSpreadAt = -1;
+
     let failOnShorthandAssign;
     if (refShorthandDefaultPos) {
       failOnShorthandAssign = false;
@@ -138,7 +152,7 @@ export default class ExpressionParser extends LValParser {
       failOnShorthandAssign = true;
     }
 
-    if (this.match(tt.parenL) || this.match(tt.name) || this.match(tt._yield)) {
+    if (this.match(tt.parenL) || this.match(tt.name)) {
       this.state.potentialArrowAt = this.state.start;
     }
 
@@ -169,21 +183,26 @@ export default class ExpressionParser extends LValParser {
 
       this.checkLVal(left, undefined, undefined, "assignment expression");
 
-      if (left.extra && left.extra.parenthesized) {
-        let errorMsg;
-        if (left.type === "ObjectPattern") {
-          errorMsg = "`({a}) = 0` use `({a} = 0)`";
-        } else if (left.type === "ArrayPattern") {
-          errorMsg = "`([a]) = 0` use `([a] = 0)`";
-        }
-        if (errorMsg) {
-          this.raise(
-            left.start,
-            `You're trying to assign to a parenthesized expression, eg. instead of ${errorMsg}`,
-          );
-        }
+      let patternErrorMsg;
+      let elementName;
+      if (left.type === "ObjectPattern") {
+        patternErrorMsg = "`({a}) = 0` use `({a} = 0)`";
+        elementName = "property";
+      } else if (left.type === "ArrayPattern") {
+        patternErrorMsg = "`([a]) = 0` use `([a] = 0)`";
+        elementName = "element";
       }
 
+      if (patternErrorMsg && left.extra && left.extra.parenthesized) {
+        this.raise(
+          left.start,
+          `You're trying to assign to a parenthesized expression, eg. instead of ${patternErrorMsg}`,
+        );
+      }
+
+      if (elementName) this.checkCommaAfterRestFromSpread(elementName);
+      this.state.commaAfterSpreadAt = oldCommaAfterSpreadAt;
+
       this.next();
       node.right = this.parseMaybeAssign(noIn);
       return this.finishNode(node, "AssignmentExpression");
@@ -191,6 +210,8 @@ export default class ExpressionParser extends LValParser {
       this.unexpected(refShorthandDefaultPos.start);
     }
 
+    this.state.commaAfterSpreadAt = oldCommaAfterSpreadAt;
+
     return left;
   }
 
@@ -398,7 +419,13 @@ export default class ExpressionParser extends LValParser {
   // Parse unary operators, both prefix and postfix.
 
   parseMaybeUnary(refShorthandDefaultPos: ?Pos): N.Expression {
-    if (this.state.type.prefix) {
+    if (
+      this.isContextual("await") &&
+      (this.state.inAsync ||
+        (!this.state.inFunction && this.options.allowAwaitOutsideFunction))
+    ) {
+      return this.parseAwait();
+    } else if (this.state.type.prefix) {
       const node = this.startNode();
       const update = this.match(tt.incDec);
       node.operator = this.state.value;
@@ -515,7 +542,7 @@ export default class ExpressionParser extends LValParser {
     } else if (this.match(tt.questionDot)) {
       this.expectPlugin("optionalChaining");
       state.optionalChainMember = true;
-      if (noCalls && this.lookahead().type == tt.parenL) {
+      if (noCalls && this.lookahead().type === tt.parenL) {
         state.stop = true;
         return base;
       }
@@ -570,9 +597,11 @@ export default class ExpressionParser extends LValParser {
       return this.finishNode(node, "MemberExpression");
     } else if (!noCalls && this.match(tt.parenL)) {
       const oldMaybeInArrowParameters = this.state.maybeInArrowParameters;
-      const oldYOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
+      const oldYieldPos = this.state.yieldPos;
+      const oldAwaitPos = this.state.awaitPos;
       this.state.maybeInArrowParameters = true;
-      this.state.yieldOrAwaitInPossibleArrowParameters = null;
+      this.state.yieldPos = 0;
+      this.state.awaitPos = 0;
 
       const possibleAsync = this.atPossibleAsync(base);
       this.next();
@@ -580,15 +609,13 @@ export default class ExpressionParser extends LValParser {
       let node = this.startNodeAt(startPos, startLoc);
       node.callee = base;
 
-      // TODO: Clean up/merge this into `this.state` or a class like acorn's
-      // `DestructuringErrors` alongside refShorthandDefaultPos and
-      // refNeedsArrowPos.
-      const refTrailingCommaPos: Pos = { start: -1 };
+      const oldCommaAfterSpreadAt = this.state.commaAfterSpreadAt;
+      this.state.commaAfterSpreadAt = -1;
 
       node.arguments = this.parseCallExpressionArguments(
         tt.parenR,
         possibleAsync,
-        refTrailingCommaPos,
+        base.type === "Import",
       );
       if (!state.optionalChainMember) {
         this.finishCallExpression(node);
@@ -599,28 +626,26 @@ export default class ExpressionParser extends LValParser {
       if (possibleAsync && this.shouldParseAsyncArrow()) {
         state.stop = true;
 
-        if (refTrailingCommaPos.start > -1) {
-          this.raise(
-            refTrailingCommaPos.start,
-            "A trailing comma is not permitted after the rest element",
-          );
-        }
+        this.checkCommaAfterRestFromSpread("parameter");
 
         node = this.parseAsyncArrowFromCallExpression(
           this.startNodeAt(startPos, startLoc),
           node,
         );
-        this.state.yieldOrAwaitInPossibleArrowParameters = oldYOAIPAP;
+        this.checkYieldAwaitInDefaultParams();
+        this.state.yieldPos = oldYieldPos;
+        this.state.awaitPos = oldAwaitPos;
       } else {
         this.toReferencedListDeep(node.arguments);
 
         // We keep the old value if it isn't null, for cases like
         //   (x = async(yield)) => {}
-        this.state.yieldOrAwaitInPossibleArrowParameters =
-          this.state.yieldOrAwaitInPossibleArrowParameters || oldYOAIPAP;
+        this.state.yieldPos = oldYieldPos || this.state.yieldPos;
+        this.state.awaitPos = oldAwaitPos || this.state.awaitPos;
       }
 
       this.state.maybeInArrowParameters = oldMaybeInArrowParameters;
+      this.state.commaAfterSpreadAt = oldCommaAfterSpreadAt;
 
       return node;
     } else if (this.match(tt.backQuote)) {
@@ -700,7 +725,7 @@ export default class ExpressionParser extends LValParser {
   parseCallExpressionArguments(
     close: TokenType,
     possibleAsyncArrow: boolean,
-    refTrailingCommaPos?: Pos,
+    dynamicImport?: boolean,
   ): $ReadOnlyArray<?N.Expression> {
     const elts = [];
     let innerParenStart;
@@ -711,7 +736,15 @@ export default class ExpressionParser extends LValParser {
         first = false;
       } else {
         this.expect(tt.comma);
-        if (this.eat(close)) break;
+        if (this.eat(close)) {
+          if (dynamicImport) {
+            this.raise(
+              this.state.lastTokStart,
+              "Trailing comma is disallowed inside import(...) arguments",
+            );
+          }
+          break;
+        }
       }
 
       // we need to make sure that if this is an async arrow functions,
@@ -725,7 +758,6 @@ export default class ExpressionParser extends LValParser {
           false,
           possibleAsyncArrow ? { start: 0 } : undefined,
           possibleAsyncArrow ? { start: 0 } : undefined,
-          possibleAsyncArrow ? refTrailingCommaPos : undefined,
         ),
       );
     }
@@ -826,29 +858,12 @@ export default class ExpressionParser extends LValParser {
         this.next();
         return this.finishNode(node, "ThisExpression");
 
-      case tt._yield:
-        if (this.state.inGenerator) this.unexpected();
-
       case tt.name: {
         node = this.startNode();
-        const allowAwait =
-          this.state.value === "await" &&
-          (this.state.inAsync ||
-            (!this.state.inFunction && this.options.allowAwaitOutsideFunction));
-
         const containsEsc = this.state.containsEsc;
-        const allowYield = this.shouldAllowYieldIdentifier();
-        const id = this.parseIdentifier(allowAwait || allowYield);
+        const id = this.parseIdentifier();
 
-        if (id.name === "await") {
-          if (
-            this.state.inAsync ||
-            this.inModule ||
-            (!this.state.inFunction && this.options.allowAwaitOutsideFunction)
-          ) {
-            return this.parseAwait(node);
-          }
-        } else if (
+        if (
           !containsEsc &&
           id.name === "async" &&
           this.match(tt._function) &&
@@ -858,28 +873,23 @@ export default class ExpressionParser extends LValParser {
           return this.parseFunction(node, false, false, true);
         } else if (
           canBeArrow &&
-          !this.canInsertSemicolon() &&
           id.name === "async" &&
-          this.match(tt.name)
+          this.match(tt.name) &&
+          !this.canInsertSemicolon()
         ) {
-          const oldYOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
           const oldInAsync = this.state.inAsync;
-          this.state.yieldOrAwaitInPossibleArrowParameters = null;
           this.state.inAsync = true;
           const params = [this.parseIdentifier()];
           this.expect(tt.arrow);
           // let foo = async bar => {};
           this.parseArrowExpression(node, params, true);
-          this.state.yieldOrAwaitInPossibleArrowParameters = oldYOAIPAP;
           this.state.inAsync = oldInAsync;
           return node;
         }
 
-        if (canBeArrow && !this.canInsertSemicolon() && this.eat(tt.arrow)) {
-          const oldYOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
-          this.state.yieldOrAwaitInPossibleArrowParameters = null;
-          this.parseArrowExpression(node, [id]);
-          this.state.yieldOrAwaitInPossibleArrowParameters = oldYOAIPAP;
+        if (canBeArrow && this.match(tt.arrow) && !this.canInsertSemicolon()) {
+          this.next();
+          this.parseArrowExpression(node, [id], false);
           return node;
         }
 
@@ -1135,7 +1145,11 @@ export default class ExpressionParser extends LValParser {
 
     const node = this.startNodeAt(startPos, startLoc);
     this.addExtra(node, "rawValue", value);
-    this.addExtra(node, "raw", this.input.slice(startPos, this.state.end));
+    this.addExtra(
+      node,
+      "raw",
+      this.state.input.slice(startPos, this.state.end),
+    );
     node.value = value;
     this.next();
     return this.finishNode(node, type);
@@ -1156,9 +1170,11 @@ export default class ExpressionParser extends LValParser {
     this.expect(tt.parenL);
 
     const oldMaybeInArrowParameters = this.state.maybeInArrowParameters;
-    const oldYOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
+    const oldYieldPos = this.state.yieldPos;
+    const oldAwaitPos = this.state.awaitPos;
     this.state.maybeInArrowParameters = true;
-    this.state.yieldOrAwaitInPossibleArrowParameters = null;
+    this.state.yieldPos = 0;
+    this.state.awaitPos = 0;
 
     const innerStartPos = this.state.start;
     const innerStartLoc = this.state.startLoc;
@@ -1192,14 +1208,7 @@ export default class ExpressionParser extends LValParser {
           ),
         );
 
-        if (this.match(tt.comma)) {
-          const nextTokenType = this.lookahead().type;
-          const errorMessage =
-            nextTokenType === tt.parenR
-              ? "A trailing comma is not permitted after the rest element"
-              : "Rest parameter must be last formal parameter";
-          this.raise(this.state.start, errorMessage);
-        }
+        this.checkCommaAfterRest(tt.parenR, "parameter");
 
         break;
       } else {
@@ -1226,21 +1235,23 @@ export default class ExpressionParser extends LValParser {
       this.shouldParseArrow() &&
       (arrowNode = this.parseArrow(arrowNode))
     ) {
+      this.checkYieldAwaitInDefaultParams();
+      this.state.yieldPos = oldYieldPos;
+      this.state.awaitPos = oldAwaitPos;
       for (const param of exprList) {
         if (param.extra && param.extra.parenthesized) {
           this.unexpected(param.extra.parenStart);
         }
       }
 
-      this.parseArrowExpression(arrowNode, exprList);
-      this.state.yieldOrAwaitInPossibleArrowParameters = oldYOAIPAP;
+      this.parseArrowExpression(arrowNode, exprList, false);
       return arrowNode;
     }
 
     // We keep the old value if it isn't null, for cases like
     //   (x = (yield)) => {}
-    this.state.yieldOrAwaitInPossibleArrowParameters =
-      this.state.yieldOrAwaitInPossibleArrowParameters || oldYOAIPAP;
+    this.state.yieldPos = oldYieldPos || this.state.yieldPos;
+    this.state.awaitPos = oldAwaitPos || this.state.awaitPos;
 
     if (!exprList.length) {
       this.unexpected(this.state.lastTokStart);
@@ -1312,7 +1323,10 @@ export default class ExpressionParser extends LValParser {
     }
 
     node.callee = this.parseNoCallExpr();
-    if (
+
+    if (node.callee.type === "Import") {
+      this.raise(node.callee.start, "Cannot use new with import(...)");
+    } else if (
       node.callee.type === "OptionalMemberExpression" ||
       node.callee.type === "OptionalCallExpression"
     ) {
@@ -1320,13 +1334,13 @@ export default class ExpressionParser extends LValParser {
         this.state.lastTokEnd,
         "constructors in/after an Optional Chain are not allowed",
       );
-    }
-    if (this.eat(tt.questionDot)) {
+    } else if (this.eat(tt.questionDot)) {
       this.raise(
         this.state.start,
         "constructors in/after an Optional Chain are not allowed",
       );
     }
+
     this.parseNewArguments(node);
     return this.finishNode(node, "NewExpression");
   }
@@ -1358,7 +1372,7 @@ export default class ExpressionParser extends LValParser {
       }
     }
     elem.value = {
-      raw: this.input
+      raw: this.state.input
         .slice(this.state.start, this.state.end)
         .replace(/\r\n?/g, "\n"),
       cooked: this.state.value,
@@ -1398,8 +1412,6 @@ export default class ExpressionParser extends LValParser {
     node.properties = [];
     this.next();
 
-    let firstRestLocation = null;
-
     while (!this.eat(tt.braceR)) {
       if (first) {
         first = false;
@@ -1435,34 +1447,14 @@ export default class ExpressionParser extends LValParser {
 
       if (this.match(tt.ellipsis)) {
         prop = this.parseSpread(isPattern ? { start: 0 } : undefined);
-        if (isPattern) {
-          this.toAssignable(prop, true, "object pattern");
-        }
         node.properties.push(prop);
         if (isPattern) {
-          const position = this.state.start;
-          if (firstRestLocation !== null) {
-            this.unexpected(
-              firstRestLocation,
-              "Cannot have multiple rest elements when destructuring",
-            );
-          } else if (this.eat(tt.braceR)) {
-            break;
-          } else if (
-            this.match(tt.comma) &&
-            this.lookahead().type === tt.braceR
-          ) {
-            this.unexpected(
-              position,
-              "A trailing comma is not permitted after the rest element",
-            );
-          } else {
-            firstRestLocation = position;
-            continue;
-          }
-        } else {
-          continue;
+          this.toAssignable(prop, true, "object pattern");
+          this.checkCommaAfterRest(tt.braceR, "property");
+          this.expect(tt.braceR);
+          break;
         }
+        continue;
       }
 
       prop.method = false;
@@ -1519,13 +1511,6 @@ export default class ExpressionParser extends LValParser {
       node.properties.push(prop);
     }
 
-    if (firstRestLocation !== null) {
-      this.unexpected(
-        firstRestLocation,
-        "The rest element has to be the last element when destructuring",
-      );
-    }
-
     if (decorators.length) {
       this.raise(
         this.state.start,
@@ -1734,21 +1719,28 @@ export default class ExpressionParser extends LValParser {
     const oldInMethod = this.state.inMethod;
     const oldInAsync = this.state.inAsync;
     const oldInGenerator = this.state.inGenerator;
+    const oldYieldPos = this.state.yieldPos;
+    const oldAwaitPos = this.state.awaitPos;
     this.state.inFunction = true;
     this.state.inMethod = node.kind || true;
     this.state.inAsync = isAsync;
     this.state.inGenerator = isGenerator;
+    this.state.yieldPos = 0;
+    this.state.awaitPos = 0;
 
     this.initFunction(node, isAsync);
     node.generator = !!isGenerator;
     const allowModifiers = isConstructor; // For TypeScript parameter properties
     this.parseFunctionParams((node: any), allowModifiers);
+    this.checkYieldAwaitInDefaultParams();
     this.parseFunctionBodyAndFinish(node, type);
 
     this.state.inFunction = oldInFunc;
     this.state.inMethod = oldInMethod;
     this.state.inAsync = oldInAsync;
     this.state.inGenerator = oldInGenerator;
+    this.state.yieldPos = oldYieldPos;
+    this.state.awaitPos = oldAwaitPos;
 
     return node;
   }
@@ -1758,44 +1750,33 @@ export default class ExpressionParser extends LValParser {
   // assignable list.
   parseArrowExpression(
     node: N.ArrowFunctionExpression,
-    params?: ?(N.Expression[]),
-    isAsync?: boolean,
+    params: ?(N.Expression[]),
+    isAsync: boolean,
   ): N.ArrowFunctionExpression {
-    // if we got there, it's no more "yield in possible arrow parameters";
-    // it's just "yield in arrow parameters"
-    const yOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
-    if (yOAIPAP) {
-      if (yOAIPAP.type === "YieldExpression") {
-        this.raise(
-          yOAIPAP.start,
-          "yield is not allowed in the parameters of an arrow function" +
-            " inside a generator",
-        );
-      } else {
-        this.raise(
-          yOAIPAP.start,
-          "await is not allowed in the parameters of an arrow function" +
-            " inside an async function",
-        );
-      }
-    }
+    this.initFunction(node, isAsync);
 
     const oldInFunc = this.state.inFunction;
-    this.state.inFunction = true;
-    this.initFunction(node, isAsync);
-    if (params) this.setArrowFunctionParameters(node, params);
-
     const oldInAsync = this.state.inAsync;
     const oldInGenerator = this.state.inGenerator;
     const oldMaybeInArrowParameters = this.state.maybeInArrowParameters;
+    const oldYieldPos = this.state.yieldPos;
+    const oldAwaitPos = this.state.awaitPos;
+    this.state.inFunction = true;
     this.state.inAsync = isAsync;
     this.state.inGenerator = false;
     this.state.maybeInArrowParameters = false;
+    this.state.yieldPos = 0;
+    this.state.awaitPos = 0;
+
+    if (params) this.setArrowFunctionParameters(node, params);
     this.parseFunctionBody(node, true);
+
     this.state.inAsync = oldInAsync;
     this.state.inGenerator = oldInGenerator;
     this.state.inFunction = oldInFunc;
     this.state.maybeInArrowParameters = oldMaybeInArrowParameters;
+    this.state.yieldPos = oldYieldPos;
+    this.state.awaitPos = oldAwaitPos;
 
     return this.finishNode(node, "ArrowFunctionExpression");
   }
@@ -1845,17 +1826,14 @@ export default class ExpressionParser extends LValParser {
     if (isExpression) {
       node.body = this.parseMaybeAssign();
     } else {
-      // Start a new scope with regard to labels and the `inGenerator`
+      // Start a new scope with regard to labels
       // flag (restore them to their old value afterwards).
-      const oldInGen = this.state.inGenerator;
       const oldInFunc = this.state.inFunction;
       const oldLabels = this.state.labels;
-      this.state.inGenerator = node.generator;
       this.state.inFunction = true;
       this.state.labels = [];
       node.body = this.parseBlock(true);
       this.state.inFunction = oldInFunc;
-      this.state.inGenerator = oldInGen;
       this.state.labels = oldLabels;
     }
 
@@ -1923,7 +1901,6 @@ export default class ExpressionParser extends LValParser {
     allowEmpty: ?boolean,
     refShorthandDefaultPos: ?Pos,
     refNeedsArrowPos: ?Pos,
-    refTrailingCommaPos?: Pos,
   ): ?N.Expression {
     let elt;
     if (allowEmpty && this.match(tt.comma)) {
@@ -1936,10 +1913,6 @@ export default class ExpressionParser extends LValParser {
         spreadNodeStartPos,
         spreadNodeStartLoc,
       );
-
-      if (refTrailingCommaPos && this.match(tt.comma)) {
-        refTrailingCommaPos.start = this.state.start;
-      }
     } else {
       elt = this.parseMaybeAssign(
         false,
@@ -1970,15 +1943,6 @@ export default class ExpressionParser extends LValParser {
   }
 
   parseIdentifierName(pos: number, liberal?: boolean): string {
-    if (!liberal) {
-      this.checkReservedWord(
-        this.state.value,
-        this.state.start,
-        !!this.state.type.keyword,
-        false,
-      );
-    }
-
     let name: string;
 
     if (this.match(tt.name)) {
@@ -1994,7 +1958,8 @@ export default class ExpressionParser extends LValParser {
       if (
         (name === "class" || name === "function") &&
         (this.state.lastTokEnd !== this.state.lastTokStart + 1 ||
-          this.input.charCodeAt(this.state.lastTokStart) !== charCodes.dot)
+          this.state.input.charCodeAt(this.state.lastTokStart) !==
+            charCodes.dot)
       ) {
         this.state.context.pop();
       }
@@ -2002,11 +1967,17 @@ export default class ExpressionParser extends LValParser {
       throw this.unexpected();
     }
 
-    if (!liberal && name === "await" && this.state.inAsync) {
-      this.raise(pos, "invalid use of await inside of an async function");
+    if (!liberal) {
+      this.checkReservedWord(
+        name,
+        this.state.start,
+        !!this.state.type.keyword,
+        false,
+      );
     }
 
     this.next();
+
     return name;
   }
 
@@ -2016,43 +1987,58 @@ export default class ExpressionParser extends LValParser {
     checkKeywords: boolean,
     isBinding: boolean,
   ): void {
-    if (
-      this.state.strict &&
-      (reservedWords.strict(word) ||
-        (isBinding && reservedWords.strictBind(word)))
-    ) {
-      this.raise(startLoc, word + " is a reserved word in strict mode");
-    }
-
-    if (this.state.inGenerator && word === "yield") {
+    const state = this.state;
+    if (state.inGenerator && word === "yield") {
       this.raise(
         startLoc,
-        "yield is a reserved word inside generator functions",
+        "Can not use 'yield' as identifier inside a generator",
       );
     }
 
-    if (this.state.inClassProperty && word === "arguments") {
+    if (state.inAsync && word === "await") {
+      this.raise(
+        startLoc,
+        "Can not use 'await' as identifier inside an async function",
+      );
+    }
+
+    if (state.inClassProperty && word === "arguments") {
       this.raise(
         startLoc,
         "'arguments' is not allowed in class field initializer",
       );
     }
+    if (checkKeywords && isKeyword(word)) {
+      this.raise(startLoc, `Unexpected keyword '${word}'`);
+    }
 
-    if (this.isReservedWord(word) || (checkKeywords && this.isKeyword(word))) {
-      this.raise(startLoc, word + " is a reserved word");
+    const reservedTest = !state.strict
+      ? isReservedWord
+      : isBinding
+      ? isStrictBindReservedWord
+      : isStrictReservedWord;
+
+    if (reservedTest(word, this.inModule)) {
+      if (!state.inAsync && word === "await") {
+        this.raise(
+          startLoc,
+          "Can not use keyword 'await' outside an async function",
+        );
+      }
+      this.raise(startLoc, `Unexpected reserved word '${word}'`);
     }
   }
 
   // Parses await expression inside async function.
 
-  parseAwait(node: N.AwaitExpression): N.AwaitExpression {
-    // istanbul ignore next: this condition is checked at the call site so won't be hit here
-    if (
-      !this.state.inAsync &&
-      (this.state.inFunction || !this.options.allowAwaitOutsideFunction)
-    ) {
-      this.unexpected();
+  parseAwait(): N.AwaitExpression {
+    if (!this.state.awaitPos) {
+      this.state.awaitPos = this.state.start;
     }
+    const node = this.startNode();
+
+    this.next();
+
     if (this.state.inParameters) {
       this.raise(
         node.start,
@@ -2065,14 +2051,6 @@ export default class ExpressionParser extends LValParser {
         "await* has been removed from the async functions proposal. Use Promise.all() instead.",
       );
     }
-    if (
-      this.state.maybeInArrowParameters &&
-      // We only set yieldOrAwaitInPossibleArrowParameters if we haven't already
-      // found a possible invalid AwaitExpression.
-      !this.state.yieldOrAwaitInPossibleArrowParameters
-    ) {
-      this.state.yieldOrAwaitInPossibleArrowParameters = node;
-    }
 
     node.argument = this.parseMaybeUnary();
     return this.finishNode(node, "AwaitExpression");
@@ -2080,32 +2058,27 @@ export default class ExpressionParser extends LValParser {
 
   // Parses yield expression inside generator.
 
-  parseYield(): N.YieldExpression {
+  parseYield(noIn?: ?boolean): N.YieldExpression {
+    if (!this.state.yieldPos) {
+      this.state.yieldPos = this.state.start;
+    }
     const node = this.startNode();
 
     if (this.state.inParameters) {
       this.raise(node.start, "yield is not allowed in generator parameters");
     }
-    if (
-      this.state.maybeInArrowParameters &&
-      // We only set yieldOrAwaitInPossibleArrowParameters if we haven't already
-      // found a possible invalid YieldExpression.
-      !this.state.yieldOrAwaitInPossibleArrowParameters
-    ) {
-      this.state.yieldOrAwaitInPossibleArrowParameters = node;
-    }
 
     this.next();
     if (
       this.match(tt.semi) ||
-      this.canInsertSemicolon() ||
-      (!this.match(tt.star) && !this.state.type.startsExpr)
+      (!this.match(tt.star) && !this.state.type.startsExpr) ||
+      this.canInsertSemicolon()
     ) {
       node.delegate = false;
       node.argument = null;
     } else {
       node.delegate = this.eat(tt.star);
-      node.argument = this.parseMaybeAssign();
+      node.argument = this.parseMaybeAssign(noIn);
     }
     return this.finishNode(node, "YieldExpression");
   }

packages/babel-parser/src/parser/index.js

@@ -6,9 +6,7 @@ import type { PluginList } from "../plugin-utils";
 import { getOptions } from "../options";
 import StatementParser from "./statement";
 
-export type PluginsMap = {
-  [key: string]: { [option: string]: any },
-};
+export type PluginsMap = Map<string, { [string]: any }>;
 
 export default class Parser extends StatementParser {
   // Forward-declaration so typescript plugin can override jsx plugin
@@ -22,7 +20,6 @@ export default class Parser extends StatementParser {
 
     this.options = options;
     this.inModule = this.options.sourceType === "module";
-    this.input = input;
     this.plugins = pluginsMap(this.options.plugins);
     this.filename = options.sourceFilename;
   }
@@ -36,10 +33,10 @@ export default class Parser extends StatementParser {
 }
 
 function pluginsMap(plugins: PluginList): PluginsMap {
-  const pluginMap: PluginsMap = (Object.create(null): Object);
+  const pluginMap: PluginsMap = new Map();
   for (const plugin of plugins) {
-    const [name, options = {}] = Array.isArray(plugin) ? plugin : [plugin, {}];
-    if (!pluginMap[name]) pluginMap[name] = options || {};
+    const [name, options] = Array.isArray(plugin) ? plugin : [plugin, {}];
+    if (!pluginMap.has(name)) pluginMap.set(name, options || {});
   }
   return pluginMap;
 }

packages/babel-parser/src/parser/location.js

@@ -21,7 +21,7 @@ export default class LocationParser extends CommentsParser {
       code?: string,
     } = {},
   ): empty {
-    const loc = getLineInfo(this.input, pos);
+    const loc = getLineInfo(this.state.input, pos);
     message += ` (${loc.line}:${loc.column})`;
     // $FlowIgnore
     const err: SyntaxError & { pos: number, loc: Position } = new SyntaxError(

packages/babel-parser/src/parser/lval.js

@@ -14,16 +14,11 @@ import type {
   SpreadElement,
 } from "../types";
 import type { Pos, Position } from "../util/location";
+import { isStrictBindReservedWord } from "../util/identifier";
 import { NodeUtils } from "./node";
 
 export default class LValParser extends NodeUtils {
   // Forward-declaration: defined in expression.js
-  +checkReservedWord: (
-    word: string,
-    startLoc: number,
-    checkKeywords: boolean,
-    isBinding: boolean,
-  ) => void;
   +parseIdentifier: (liberal?: boolean) => Identifier;
   +parseMaybeAssign: (
     noIn?: ?boolean,
@@ -56,9 +51,13 @@ export default class LValParser extends NodeUtils {
 
         case "ObjectExpression":
           node.type = "ObjectPattern";
-          for (let index = 0; index < node.properties.length; index++) {
-            const prop = node.properties[index];
-            const isLast = index === node.properties.length - 1;
+          for (
+            let i = 0, length = node.properties.length, last = length - 1;
+            i < length;
+            i++
+          ) {
+            const prop = node.properties[i];
+            const isLast = i === last;
             this.toAssignableObjectExpressionProp(prop, isBinding, isLast);
           }
           break;
@@ -122,10 +121,7 @@ export default class LValParser extends NodeUtils {
 
       this.raise(prop.key.start, error);
     } else if (prop.type === "SpreadElement" && !isLast) {
-      this.raise(
-        prop.start,
-        "The rest element has to be the last element when destructuring",
-      );
+      this.raiseRestNotLast(prop.start, "property");
     } else {
       this.toAssignable(prop, isBinding, "object destructuring pattern");
     }
@@ -148,12 +144,10 @@ export default class LValParser extends NodeUtils {
         const arg = last.argument;
         this.toAssignable(arg, isBinding, contextDescription);
         if (
-          [
-            "Identifier",
-            "MemberExpression",
-            "ArrayPattern",
-            "ObjectPattern",
-          ].indexOf(arg.type) === -1
+          arg.type !== "Identifier" &&
+          arg.type !== "MemberExpression" &&
+          arg.type !== "ArrayPattern" &&
+          arg.type !== "ObjectPattern"
         ) {
           this.unexpected(arg.start);
         }
@@ -162,13 +156,12 @@ export default class LValParser extends NodeUtils {
     }
     for (let i = 0; i < end; i++) {
       const elt = exprList[i];
-      if (elt && elt.type === "SpreadElement") {
-        this.raise(
-          elt.start,
-          "The rest element has to be the last element when destructuring",
-        );
+      if (elt) {
+        this.toAssignable(elt, isBinding, contextDescription);
+        if (elt.type === "RestElement") {
+          this.raiseRestNotLast(elt.start, "element");
+        }
       }
-      if (elt) this.toAssignable(elt, isBinding, contextDescription);
     }
     return exprList;
   }
@@ -199,10 +192,10 @@ export default class LValParser extends NodeUtils {
 
   // Parses spread element.
 
-  parseSpread<T: RestElement | SpreadElement>(
+  parseSpread(
     refShorthandDefaultPos: ?Pos,
     refNeedsArrowPos?: ?Pos,
-  ): T {
+  ): SpreadElement {
     const node = this.startNode();
     this.next();
     node.argument = this.parseMaybeAssign(
@@ -211,6 +204,11 @@ export default class LValParser extends NodeUtils {
       undefined,
       refNeedsArrowPos,
     );
+
+    if (this.state.commaAfterSpreadAt === -1 && this.match(tt.comma)) {
+      this.state.commaAfterSpreadAt = this.state.start;
+    }
+
     return this.finishNode(node, "SpreadElement");
   }
 
@@ -221,22 +219,11 @@ export default class LValParser extends NodeUtils {
     return this.finishNode(node, "RestElement");
   }
 
-  shouldAllowYieldIdentifier(): boolean {
-    return (
-      this.match(tt._yield) && !this.state.strict && !this.state.inGenerator
-    );
-  }
-
-  parseBindingIdentifier(): Identifier {
-    return this.parseIdentifier(this.shouldAllowYieldIdentifier());
-  }
-
   // Parses lvalue (assignable) atom.
   parseBindingAtom(): Pattern {
     switch (this.state.type) {
-      case tt._yield:
       case tt.name:
-        return this.parseBindingIdentifier();
+        return this.parseIdentifier();
 
       case tt.bracketL: {
         const node = this.startNode();
@@ -273,20 +260,13 @@ export default class LValParser extends NodeUtils {
         break;
       } else if (this.match(tt.ellipsis)) {
         elts.push(this.parseAssignableListItemTypes(this.parseRest()));
-        if (
-          this.state.inFunction &&
-          this.state.inParameters &&
-          this.match(tt.comma)
-        ) {
-          const nextTokenType = this.lookahead().type;
-          const errorMessage =
-            nextTokenType === tt.parenR
-              ? "A trailing comma is not permitted after the rest element"
-              : "Rest parameter must be last formal parameter";
-          this.raise(this.state.start, errorMessage);
-        } else {
-          this.expect(close);
-        }
+        this.checkCommaAfterRest(
+          close,
+          this.state.inFunction && this.state.inParameters
+            ? "parameter"
+            : "element",
+        );
+        this.expect(close);
         break;
       } else {
         const decorators = [];
@@ -351,7 +331,17 @@ export default class LValParser extends NodeUtils {
   ): void {
     switch (expr.type) {
       case "Identifier":
-        this.checkReservedWord(expr.name, expr.start, false, true);
+        if (
+          this.state.strict &&
+          isStrictBindReservedWord(expr.name, this.inModule)
+        ) {
+          this.raise(
+            expr.start,
+            `${isBinding ? "Binding" : "Assigning to"} '${
+              expr.name
+            }' in strict mode`,
+          );
+        }
 
         if (checkClashes) {
           // we need to prefix this with an underscore for the cases where we have a key of
@@ -432,12 +422,35 @@ export default class LValParser extends NodeUtils {
   }
 
   checkToRestConversion(node: SpreadElement): void {
-    const validArgumentTypes = ["Identifier", "MemberExpression"];
-
-    if (validArgumentTypes.indexOf(node.argument.type) !== -1) {
-      return;
+    if (
+      node.argument.type !== "Identifier" &&
+      node.argument.type !== "MemberExpression"
+    ) {
+      this.raise(node.argument.start, "Invalid rest operator's argument");
     }
+  }
 
-    this.raise(node.argument.start, "Invalid rest operator's argument");
+  checkCommaAfterRest(close: TokenType, kind: string): void {
+    if (this.match(tt.comma)) {
+      if (this.lookahead().type === close) {
+        this.raiseCommaAfterRest(this.state.start, kind);
+      } else {
+        this.raiseRestNotLast(this.state.start, kind);
+      }
+    }
+  }
+
+  checkCommaAfterRestFromSpread(kind: string): void {
+    if (this.state.commaAfterSpreadAt > -1) {
+      this.raiseCommaAfterRest(this.state.commaAfterSpreadAt, kind);
+    }
+  }
+
+  raiseCommaAfterRest(pos: number, kind: string) {
+    this.raise(pos, `A trailing comma is not permitted after the rest ${kind}`);
+  }
+
+  raiseRestNotLast(pos: number, kind: string) {
+    this.raise(pos, `The rest ${kind} must be the last ${kind}`);
   }
 }

packages/babel-parser/src/parser/node.js

@@ -7,8 +7,6 @@ import type { Comment, Node as NodeType, NodeBase } from "../types";
 
 // Start an AST node, attaching a start offset.
 
-const commentKeys = ["leadingComments", "trailingComments", "innerComments"];
-
 class Node implements NodeBase {
   constructor(parser: Parser, pos: number, loc: Position) {
     this.type = "";
@@ -31,16 +29,22 @@ class Node implements NodeBase {
 
   __clone(): this {
     // $FlowIgnore
-    const node2: any = new Node();
-    Object.keys(this).forEach(key => {
+    const newNode: any = new Node();
+    const keys = Object.keys(this);
+    for (let i = 0, length = keys.length; i < length; i++) {
+      const key = keys[i];
       // Do not clone comments that are already attached to the node
-      if (commentKeys.indexOf(key) < 0) {
+      if (
+        key !== "leadingComments" &&
+        key !== "trailingComments" &&
+        key !== "innerComments"
+      ) {
         // $FlowIgnore
-        node2[key] = this[key];
+        newNode[key] = this[key];
       }
-    });
+    }
 
-    return node2;
+    return newNode;
   }
 }
 
@@ -87,12 +91,16 @@ export class NodeUtils extends UtilParser {
     return node;
   }
 
+  resetStartLocation(node: NodeBase, start: number, startLoc: Position): void {
+    node.start = start;
+    node.loc.start = startLoc;
+    if (this.options.ranges) node.range[0] = start;
+  }
+
   /**
    * Reset the start location of node to the start location of locationNode
    */
   resetStartLocationFromNode(node: NodeBase, locationNode: NodeBase): void {
-    node.start = locationNode.start;
-    node.loc.start = locationNode.loc.start;
-    if (this.options.ranges) node.range[0] = locationNode.range[0];
+    this.resetStartLocation(node, locationNode.start, locationNode.loc.start);
   }
 }

packages/babel-parser/src/parser/statement.js

@@ -3,8 +3,13 @@
 import * as N from "../types";
 import { types as tt, type TokenType } from "../tokenizer/types";
 import ExpressionParser from "./expression";
-import { isIdentifierChar } from "../util/identifier";
+import {
+  isIdentifierChar,
+  isIdentifierStart,
+  keywordRelationalOperator,
+} from "../util/identifier";
 import { lineBreak, skipWhiteSpace } from "../util/whitespace";
+import * as charCodes from "charcodes";
 
 // Reused empty array added for node fields that are always empty.
 
@@ -44,7 +49,7 @@ export default class StatementParser extends ExpressionParser {
     const directiveLiteral = this.startNodeAt(expr.start, expr.loc.start);
     const directive = this.startNodeAt(stmt.start, stmt.loc.start);
 
-    const raw = this.input.slice(expr.start, expr.end);
+    const raw = this.state.input.slice(expr.start, expr.end);
     const val = (directiveLiteral.value = raw.slice(1, -1)); // remove quotes
 
     this.addExtra(directiveLiteral, "raw", raw);
@@ -71,6 +76,35 @@ export default class StatementParser extends ExpressionParser {
     return this.finishNode(node, "InterpreterDirective");
   }
 
+  isLet(context: ?string): boolean {
+    if (!this.isContextual("let")) {
+      return false;
+    }
+    skipWhiteSpace.lastIndex = this.state.pos;
+    const skip = skipWhiteSpace.exec(this.state.input);
+    // $FlowIgnore
+    const next = this.state.pos + skip[0].length;
+    const nextCh = this.state.input.charCodeAt(next);
+    // For ambiguous cases, determine if a LexicalDeclaration (or only a
+    // Statement) is allowed here. If context is not empty then only a Statement
+    // is allowed. However, `let [` is an explicit negative lookahead for
+    // ExpressionStatement, so special-case it first.
+    if (nextCh === charCodes.leftSquareBracket) return true;
+    if (context) return false;
+
+    if (nextCh === charCodes.leftCurlyBrace) return true;
+
+    if (isIdentifierStart(nextCh)) {
+      let pos = next + 1;
+      while (isIdentifierChar(this.state.input.charCodeAt(pos))) {
+        ++pos;
+      }
+      const ident = this.state.input.slice(next, pos);
+      if (!keywordRelationalOperator.test(ident)) return true;
+    }
+    return false;
+  }
+
   // Parse a single statement.
   //
   // If expecting a statement and finding a slash operator, parse a
@@ -78,16 +112,22 @@ export default class StatementParser extends ExpressionParser {
   // `if (foo) /blah/.exec(foo)`, where looking at the previous token
   // does not help.
 
-  parseStatement(declaration: boolean, topLevel?: boolean): N.Statement {
+  parseStatement(context: ?string, topLevel?: boolean): N.Statement {
     if (this.match(tt.at)) {
       this.parseDecorators(true);
     }
-    return this.parseStatementContent(declaration, topLevel);
+    return this.parseStatementContent(context, topLevel);
   }
 
-  parseStatementContent(declaration: boolean, topLevel: ?boolean): N.Statement {
-    const starttype = this.state.type;
+  parseStatementContent(context: ?string, topLevel: ?boolean): N.Statement {
+    let starttype = this.state.type;
     const node = this.startNode();
+    let kind;
+
+    if (this.isLet(context)) {
+      starttype = tt._var;
+      kind = "let";
+    }
 
     // Most types of statements are recognized by the keyword they
     // start with. Many are trivial to parse, some require a bit of
@@ -104,13 +144,28 @@ export default class StatementParser extends ExpressionParser {
         return this.parseDoStatement(node);
       case tt._for:
         return this.parseForStatement(node);
-      case tt._function:
+      case tt._function: {
         if (this.lookahead().type === tt.dot) break;
-        if (!declaration) this.unexpected();
-        return this.parseFunctionStatement(node);
+        if (
+          context &&
+          (this.state.strict || (context !== "if" && context !== "label"))
+        ) {
+          this.raise(
+            this.state.start,
+            "Function declaration not allowed in this context",
+          );
+        }
+        const result = this.parseFunctionStatement(node);
 
+        // TODO: Remove this once we have proper scope tracking in place.
+        if (context && result.generator) {
+          this.unexpected(node.start);
+        }
+
+        return result;
+      }
       case tt._class:
-        if (!declaration) this.unexpected();
+        if (context) this.unexpected();
         return this.parseClass(node, true);
 
       case tt._if:
@@ -124,12 +179,11 @@ export default class StatementParser extends ExpressionParser {
       case tt._try:
         return this.parseTryStatement(node);
 
-      case tt._let:
       case tt._const:
-        if (!declaration) this.unexpected(); // NOTE: falls through to _var
-
       case tt._var:
-        return this.parseVarStatement(node, starttype);
+        kind = kind || this.state.value;
+        if (context && kind !== "var") this.unexpected();
+        return this.parseVarStatement(node, kind);
 
       case tt._while:
         return this.parseWhileStatement(node);
@@ -156,7 +210,7 @@ export default class StatementParser extends ExpressionParser {
         this.next();
 
         let result;
-        if (starttype == tt._import) {
+        if (starttype === tt._import) {
           result = this.parseImport(node);
 
           if (
@@ -189,7 +243,13 @@ export default class StatementParser extends ExpressionParser {
           const state = this.state.clone();
           this.next();
           if (this.match(tt._function) && !this.canInsertSemicolon()) {
-            this.expect(tt._function);
+            if (context) {
+              this.raise(
+                this.state.lastTokStart,
+                "Function declaration not allowed in this context",
+              );
+            }
+            this.next();
             return this.parseFunction(node, true, false, true);
           } else {
             this.state = state;
@@ -210,7 +270,7 @@ export default class StatementParser extends ExpressionParser {
       expr.type === "Identifier" &&
       this.eat(tt.colon)
     ) {
-      return this.parseLabeledStatement(node, maybeName, expr);
+      return this.parseLabeledStatement(node, maybeName, expr, context);
     } else {
       return this.parseExpressionStatement(node, expr);
     }
@@ -376,7 +436,7 @@ export default class StatementParser extends ExpressionParser {
       // outside of the loop body.
       this.withTopicForbiddingContext(() =>
         // Parse the loop body's body.
-        this.parseStatement(false),
+        this.parseStatement("do"),
       );
 
     this.state.labels.pop();
@@ -399,32 +459,36 @@ export default class StatementParser extends ExpressionParser {
     this.next();
     this.state.labels.push(loopLabel);
 
-    let forAwait = false;
-    if (this.state.inAsync && this.isContextual("await")) {
-      forAwait = true;
-      this.next();
+    let awaitAt = -1;
+    if (
+      (this.state.inAsync ||
+        (!this.state.inFunction && this.options.allowAwaitOutsideFunction)) &&
+      this.eatContextual("await")
+    ) {
+      awaitAt = this.state.lastTokStart;
     }
     this.expect(tt.parenL);
 
     if (this.match(tt.semi)) {
-      if (forAwait) {
-        this.unexpected();
+      if (awaitAt > -1) {
+        this.unexpected(awaitAt);
       }
       return this.parseFor(node, null);
     }
 
-    if (this.match(tt._var) || this.match(tt._let) || this.match(tt._const)) {
+    const isLet = this.isLet();
+    if (this.match(tt._var) || this.match(tt._const) || isLet) {
       const init = this.startNode();
-      const varKind = this.state.type;
+      const kind = isLet ? "let" : this.state.value;
       this.next();
-      this.parseVar(init, true, varKind);
+      this.parseVar(init, true, kind);
       this.finishNode(init, "VariableDeclaration");
 
       if (this.match(tt._in) || this.isContextual("of")) {
         if (init.declarations.length === 1) {
           const declaration = init.declarations[0];
           const isForInInitializer =
-            varKind === tt._var &&
+            kind === "var" &&
             declaration.init &&
             declaration.id.type != "ObjectPattern" &&
             declaration.id.type != "ArrayPattern" &&
@@ -432,12 +496,12 @@ export default class StatementParser extends ExpressionParser {
           if (this.state.strict && isForInInitializer) {
             this.raise(this.state.start, "for-in initializer in strict mode");
           } else if (isForInInitializer || !declaration.init) {
-            return this.parseForIn(node, init, forAwait);
+            return this.parseForIn(node, init, awaitAt);
           }
         }
       }
-      if (forAwait) {
-        this.unexpected();
+      if (awaitAt > -1) {
+        this.unexpected(awaitAt);
       }
       return this.parseFor(node, init);
     }
@@ -450,12 +514,12 @@ export default class StatementParser extends ExpressionParser {
         : "for-in statement";
       this.toAssignable(init, undefined, description);
       this.checkLVal(init, undefined, undefined, description);
-      return this.parseForIn(node, init, forAwait);
+      return this.parseForIn(node, init, awaitAt);
     } else if (refShorthandDefaultPos.start) {
       this.unexpected(refShorthandDefaultPos.start);
     }
-    if (forAwait) {
-      this.unexpected();
+    if (awaitAt > -1) {
+      this.unexpected(awaitAt);
     }
     return this.parseFor(node, init);
   }
@@ -468,8 +532,8 @@ export default class StatementParser extends ExpressionParser {
   parseIfStatement(node: N.IfStatement): N.IfStatement {
     this.next();
     node.test = this.parseParenExpression();
-    node.consequent = this.parseStatement(false);
-    node.alternate = this.eat(tt._else) ? this.parseStatement(false) : null;
+    node.consequent = this.parseStatement("if");
+    node.alternate = this.eat(tt._else) ? this.parseStatement("if") : null;
     return this.finishNode(node, "IfStatement");
   }
 
@@ -525,7 +589,7 @@ export default class StatementParser extends ExpressionParser {
         this.expect(tt.colon);
       } else {
         if (cur) {
-          cur.consequent.push(this.parseStatement(true));
+          cur.consequent.push(this.parseStatement(null));
         } else {
           this.unexpected();
         }
@@ -540,7 +604,9 @@ export default class StatementParser extends ExpressionParser {
   parseThrowStatement(node: N.ThrowStatement): N.ThrowStatement {
     this.next();
     if (
-      lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start))
+      lineBreak.test(
+        this.state.input.slice(this.state.lastTokEnd, this.state.start),
+      )
     ) {
       this.raise(this.state.lastTokEnd, "Illegal newline after throw");
     }
@@ -593,7 +659,7 @@ export default class StatementParser extends ExpressionParser {
 
   parseVarStatement(
     node: N.VariableDeclaration,
-    kind: TokenType,
+    kind: "var" | "let" | "const",
   ): N.VariableDeclaration {
     this.next();
     this.parseVar(node, false, kind);
@@ -612,7 +678,7 @@ export default class StatementParser extends ExpressionParser {
       // They are permitted in test expressions, outside of the loop body.
       this.withTopicForbiddingContext(() =>
         // Parse loop body.
-        this.parseStatement(false),
+        this.parseStatement("while"),
       );
 
     this.state.labels.pop();
@@ -634,7 +700,7 @@ export default class StatementParser extends ExpressionParser {
       // part of the outer context, outside of the function body.
       this.withTopicForbiddingContext(() =>
         // Parse the statement body.
-        this.parseStatement(false),
+        this.parseStatement("with"),
       );
 
     return this.finishNode(node, "WithStatement");
@@ -649,6 +715,7 @@ export default class StatementParser extends ExpressionParser {
     node: N.LabeledStatement,
     maybeName: string,
     expr: N.Identifier,
+    context: ?string,
   ): N.LabeledStatement {
     for (const label of this.state.labels) {
       if (label.name === maybeName) {
@@ -676,16 +743,13 @@ export default class StatementParser extends ExpressionParser {
       kind: kind,
       statementStart: this.state.start,
     });
-    node.body = this.parseStatement(true);
-
-    if (
-      node.body.type == "ClassDeclaration" ||
-      (node.body.type == "VariableDeclaration" && node.body.kind !== "var") ||
-      (node.body.type == "FunctionDeclaration" &&
-        (this.state.strict || node.body.generator || node.body.async))
-    ) {
-      this.raise(node.body.start, "Invalid labeled declaration");
-    }
+    node.body = this.parseStatement(
+      context
+        ? context.indexOf("label") === -1
+          ? context + "label"
+          : context
+        : "label",
+    );
 
     this.state.labels.pop();
     node.label = expr;
@@ -752,7 +816,7 @@ export default class StatementParser extends ExpressionParser {
         octalPosition = this.state.octalPosition;
       }
 
-      const stmt = this.parseStatement(true, topLevel);
+      const stmt = this.parseStatement(null, topLevel);
 
       if (directives && !parsedNonDirective && this.isValidDirective(stmt)) {
         const directive = this.stmtToDirective(stmt);
@@ -800,7 +864,7 @@ export default class StatementParser extends ExpressionParser {
       // outside of the loop body.
       this.withTopicForbiddingContext(() =>
         // Parse the loop body.
-        this.parseStatement(false),
+        this.parseStatement("for"),
       );
 
     this.state.labels.pop();
@@ -814,16 +878,16 @@ export default class StatementParser extends ExpressionParser {
   parseForIn(
     node: N.ForInOf,
     init: N.VariableDeclaration,
-    forAwait: boolean,
+    awaitAt: number,
   ): N.ForInOf {
     const type = this.match(tt._in) ? "ForInStatement" : "ForOfStatement";
-    if (forAwait) {
+    if (awaitAt > -1) {
       this.eatContextual("of");
     } else {
       this.next();
     }
     if (type === "ForOfStatement") {
-      node.await = !!forAwait;
+      node.await = awaitAt > -1;
     }
     node.left = init;
     node.right = this.parseExpression();
@@ -835,7 +899,7 @@ export default class StatementParser extends ExpressionParser {
       // They are permitted in test expressions, outside of the loop body.
       this.withTopicForbiddingContext(() =>
         // Parse loop body.
-        this.parseStatement(false),
+        this.parseStatement("for"),
       );
 
     this.state.labels.pop();
@@ -848,24 +912,24 @@ export default class StatementParser extends ExpressionParser {
   parseVar(
     node: N.VariableDeclaration,
     isFor: boolean,
-    kind: TokenType,
+    kind: "var" | "let" | "const",
   ): N.VariableDeclaration {
     const declarations = (node.declarations = []);
-    // $FlowFixMe
-    node.kind = kind.keyword;
+    const isTypescript = this.hasPlugin("typescript");
+    node.kind = kind;
     for (;;) {
       const decl = this.startNode();
-      this.parseVarHead(decl);
+      this.parseVarId(decl, kind);
       if (this.eat(tt.eq)) {
         decl.init = this.parseMaybeAssign(isFor);
       } else {
         if (
-          kind === tt._const &&
+          kind === "const" &&
           !(this.match(tt._in) || this.isContextual("of"))
         ) {
           // `const` with no initializer is allowed in TypeScript.
           // It could be a declaration like `const x: number;`.
-          if (!this.hasPlugin("typescript")) {
+          if (!isTypescript) {
             this.unexpected();
           }
         } else if (
@@ -885,7 +949,10 @@ export default class StatementParser extends ExpressionParser {
     return node;
   }
 
-  parseVarHead(decl: N.VariableDeclarator): void {
+  parseVarId(decl: N.VariableDeclarator, kind: "var" | "let" | "const"): void {
+    if ((kind === "const" || kind === "let") && this.isContextual("let")) {
+      this.unexpected(null, "let is disallowed as a lexically bound name");
+    }
     decl.id = this.parseBindingAtom();
     this.checkLVal(decl.id, true, undefined, "variable declaration");
   }
@@ -896,32 +963,28 @@ export default class StatementParser extends ExpressionParser {
   parseFunction<T: N.NormalFunction>(
     node: T,
     isStatement: boolean,
-    allowExpressionBody?: boolean,
-    isAsync?: boolean,
-    optionalId?: boolean,
+    allowExpressionBody?: boolean = false,
+    isAsync?: boolean = false,
+    optionalId?: boolean = false,
   ): T {
     const oldInFunc = this.state.inFunction;
     const oldInMethod = this.state.inMethod;
     const oldInAsync = this.state.inAsync;
     const oldInGenerator = this.state.inGenerator;
     const oldInClassProperty = this.state.inClassProperty;
+    const oldYieldPos = this.state.yieldPos;
+    const oldAwaitPos = this.state.awaitPos;
     this.state.inFunction = true;
     this.state.inMethod = false;
     this.state.inClassProperty = false;
+    this.state.yieldPos = 0;
+    this.state.awaitPos = 0;
 
     this.initFunction(node, isAsync);
 
-    if (this.match(tt.star)) {
-      node.generator = true;
-      this.next();
-    }
+    node.generator = this.eat(tt.star);
 
-    if (
-      isStatement &&
-      !optionalId &&
-      !this.match(tt.name) &&
-      !this.match(tt._yield)
-    ) {
+    if (isStatement && !optionalId && !this.match(tt.name)) {
       this.unexpected();
     }
 
@@ -938,8 +1001,8 @@ export default class StatementParser extends ExpressionParser {
       this.state.inAsync = isAsync;
       this.state.inGenerator = node.generator;
     }
-    if (this.match(tt.name) || this.match(tt._yield)) {
-      node.id = this.parseBindingIdentifier();
+    if (this.match(tt.name)) {
+      node.id = this.parseIdentifier();
     }
     if (isStatement) {
       this.state.inAsync = isAsync;
@@ -965,6 +1028,8 @@ export default class StatementParser extends ExpressionParser {
     this.state.inAsync = oldInAsync;
     this.state.inGenerator = oldInGenerator;
     this.state.inClassProperty = oldInClassProperty;
+    this.state.yieldPos = oldYieldPos;
+    this.state.awaitPos = oldAwaitPos;
 
     return node;
   }
@@ -981,6 +1046,7 @@ export default class StatementParser extends ExpressionParser {
     );
 
     this.state.inParameters = oldInParameters;
+    this.checkYieldAwaitInDefaultParams();
   }
 
   // Parse a class declaration or literal (depending on the
@@ -993,9 +1059,17 @@ export default class StatementParser extends ExpressionParser {
   ): T {
     this.next();
     this.takeDecorators(node);
+
+    // A class definition is always strict mode code.
+    const oldStrict = this.state.strict;
+    this.state.strict = true;
+
     this.parseClassId(node, isStatement, optionalId);
     this.parseClassSuper(node);
     this.parseClassBody(node);
+
+    this.state.strict = oldStrict;
+
     return this.finishNode(
       node,
       isStatement ? "ClassDeclaration" : "ClassExpression",
@@ -1020,9 +1094,6 @@ export default class StatementParser extends ExpressionParser {
   }
 
   parseClassBody(node: N.Class): void {
-    // class bodies are implicitly strict
-    const oldStrict = this.state.strict;
-    this.state.strict = true;
     this.state.classLevel++;
 
     const state = { hadConstructor: false };
@@ -1087,7 +1158,6 @@ export default class StatementParser extends ExpressionParser {
     node.body = this.finishNode(classBody, "ClassBody");
 
     this.state.classLevel--;
-    this.state.strict = oldStrict;
   }
 
   parseClassMember(
@@ -1262,7 +1332,7 @@ export default class StatementParser extends ExpressionParser {
     } else if (
       isSimple &&
       (key.name === "get" || key.name === "set") &&
-      !(this.isLineTerminator() && this.match(tt.star))
+      !(this.match(tt.star) && this.isLineTerminator())
     ) {
       // `get\n*` is an uninitialized property named 'get' followed by a generator.
       // a getter or setter
@@ -1451,35 +1521,109 @@ export default class StatementParser extends ExpressionParser {
 
   // Parses module export declaration.
 
-  // TODO: better type. Node is an N.AnyExport.
-  parseExport(node: N.Node): N.Node {
-    // export * from '...'
-    if (this.shouldParseExportStar()) {
-      this.parseExportStar(node);
-      if (node.type === "ExportAllDeclaration") return node;
-    } else if (this.isExportDefaultSpecifier()) {
-      this.expectPlugin("exportDefaultFrom");
-      const specifier = this.startNode();
-      specifier.exported = this.parseIdentifier(true);
-      const specifiers = [this.finishNode(specifier, "ExportDefaultSpecifier")];
-      node.specifiers = specifiers;
-      if (this.match(tt.comma) && this.lookahead().type === tt.star) {
-        this.expect(tt.comma);
-        const specifier = this.startNode();
-        this.expect(tt.star);
-        this.expectContextual("as");
-        specifier.exported = this.parseIdentifier();
-        specifiers.push(this.finishNode(specifier, "ExportNamespaceSpecifier"));
-      } else {
-        this.parseExportSpecifiersMaybe(node);
-      }
+  parseExport(node: N.Node): N.AnyExport {
+    const hasDefault = this.maybeParseExportDefaultSpecifier(node);
+    const parseAfterDefault = !hasDefault || this.eat(tt.comma);
+    const hasStar = parseAfterDefault && this.eatExportStar(node);
+    const hasNamespace =
+      hasStar && this.maybeParseExportNamespaceSpecifier(node);
+    const parseAfterNamespace =
+      parseAfterDefault && (!hasNamespace || this.eat(tt.comma));
+    const isFromRequired = hasDefault || hasStar;
+
+    if (hasStar && !hasNamespace) {
+      if (hasDefault) this.unexpected();
       this.parseExportFrom(node, true);
-    } else if (this.eat(tt._default)) {
+
+      return this.finishNode(node, "ExportAllDeclaration");
+    }
+
+    const hasSpecifiers = this.maybeParseExportNamedSpecifiers(node);
+
+    if (
+      (hasDefault && parseAfterDefault && !hasStar && !hasSpecifiers) ||
+      (hasNamespace && parseAfterNamespace && !hasSpecifiers)
+    ) {
+      throw this.unexpected(null, tt.braceL);
+    }
+
+    let hasDeclaration;
+    if (isFromRequired || hasSpecifiers) {
+      hasDeclaration = false;
+      this.parseExportFrom(node, isFromRequired);
+    } else {
+      hasDeclaration = this.maybeParseExportDeclaration(node);
+    }
+
+    if (isFromRequired || hasSpecifiers || hasDeclaration) {
+      this.checkExport(node, true);
+      return this.finishNode(node, "ExportNamedDeclaration");
+    }
+
+    if (this.eat(tt._default)) {
       // export default ...
       node.declaration = this.parseExportDefaultExpression();
       this.checkExport(node, true, true);
+
       return this.finishNode(node, "ExportDefaultDeclaration");
-    } else if (this.shouldParseExportDeclaration()) {
+    }
+
+    throw this.unexpected(null, tt.braceL);
+  }
+
+  // eslint-disable-next-line no-unused-vars
+  eatExportStar(node: N.Node): boolean {
+    return this.eat(tt.star);
+  }
+
+  maybeParseExportDefaultSpecifier(node: N.Node): boolean {
+    if (this.isExportDefaultSpecifier()) {
+      // export defaultObj ...
+      this.expectPlugin("exportDefaultFrom");
+      const specifier = this.startNode();
+      specifier.exported = this.parseIdentifier(true);
+      node.specifiers = [this.finishNode(specifier, "ExportDefaultSpecifier")];
+      return true;
+    }
+    return false;
+  }
+
+  maybeParseExportNamespaceSpecifier(node: N.Node): boolean {
+    if (this.isContextual("as")) {
+      if (!node.specifiers) node.specifiers = [];
+      this.expectPlugin("exportNamespaceFrom");
+
+      const specifier = this.startNodeAt(
+        this.state.lastTokStart,
+        this.state.lastTokStartLoc,
+      );
+
+      this.next();
+
+      specifier.exported = this.parseIdentifier(true);
+      node.specifiers.push(
+        this.finishNode(specifier, "ExportNamespaceSpecifier"),
+      );
+      return true;
+    }
+    return false;
+  }
+
+  maybeParseExportNamedSpecifiers(node: N.Node): boolean {
+    if (this.match(tt.braceL)) {
+      if (!node.specifiers) node.specifiers = [];
+      node.specifiers.push(...this.parseExportSpecifiers());
+
+      node.source = null;
+      node.declaration = null;
+
+      return true;
+    }
+    return false;
+  }
+
+  maybeParseExportDeclaration(node: N.Node): boolean {
+    if (this.shouldParseExportDeclaration()) {
       if (this.isContextual("async")) {
         const next = this.lookahead();
 
@@ -1492,20 +1636,16 @@ export default class StatementParser extends ExpressionParser {
       node.specifiers = [];
       node.source = null;
       node.declaration = this.parseExportDeclaration(node);
-    } else {
-      // export { x, y as z } [from '...']
-      node.declaration = null;
-      node.specifiers = this.parseExportSpecifiers();
-      this.parseExportFrom(node);
+
+      return true;
     }
-    this.checkExport(node, true);
-    return this.finishNode(node, "ExportNamedDeclaration");
+    return false;
   }
 
   isAsyncFunction() {
     if (!this.isContextual("async")) return false;
 
-    const { input, pos } = this.state;
+    const { input, pos, length } = this.state;
 
     skipWhiteSpace.lastIndex = pos;
     const skip = skipWhiteSpace.exec(input);
@@ -1517,7 +1657,7 @@ export default class StatementParser extends ExpressionParser {
     return (
       !lineBreak.test(input.slice(pos, next)) &&
       input.slice(next, next + 8) === "function" &&
-      (next + 8 === input.length || !isIdentifierChar(input.charAt(next + 8)))
+      (next + 8 === length || !isIdentifierChar(input.charCodeAt(next + 8)))
     );
   }
 
@@ -1549,11 +1689,7 @@ export default class StatementParser extends ExpressionParser {
       }
       this.parseDecorators(false);
       return this.parseClass(expr, true, true);
-    } else if (
-      this.match(tt._let) ||
-      this.match(tt._const) ||
-      this.match(tt._var)
-    ) {
+    } else if (this.match(tt._const) || this.match(tt._var) || this.isLet()) {
       return this.raise(
         this.state.start,
         "Only expressions, functions or classes are allowed as the `default` export.",
@@ -1567,12 +1703,12 @@ export default class StatementParser extends ExpressionParser {
 
   // eslint-disable-next-line no-unused-vars
   parseExportDeclaration(node: N.ExportNamedDeclaration): ?N.Declaration {
-    return this.parseStatement(true);
+    return this.parseStatement(null);
   }
 
   isExportDefaultSpecifier(): boolean {
     if (this.match(tt.name)) {
-      return this.state.value !== "async";
+      return this.state.value !== "async" && this.state.value !== "let";
     }
 
     if (!this.match(tt._default)) {
@@ -1586,17 +1722,9 @@ export default class StatementParser extends ExpressionParser {
     );
   }
 
-  parseExportSpecifiersMaybe(node: N.ExportNamedDeclaration): void {
-    if (this.eat(tt.comma)) {
-      node.specifiers = node.specifiers.concat(this.parseExportSpecifiers());
-    }
-  }
-
   parseExportFrom(node: N.ExportNamedDeclaration, expect?: boolean): void {
     if (this.eatContextual("from")) {
-      node.source = this.match(tt.string)
-        ? this.parseExprAtom()
-        : this.unexpected();
+      node.source = this.parseImportSource();
       this.checkExport(node);
     } else {
       if (expect) {
@@ -1609,39 +1737,6 @@ export default class StatementParser extends ExpressionParser {
     this.semicolon();
   }
 
-  shouldParseExportStar(): boolean {
-    return this.match(tt.star);
-  }
-
-  parseExportStar(node: N.ExportNamedDeclaration): void {
-    this.expect(tt.star);
-
-    if (this.isContextual("as")) {
-      this.parseExportNamespace(node);
-    } else {
-      this.parseExportFrom(node, true);
-      this.finishNode(node, "ExportAllDeclaration");
-    }
-  }
-
-  parseExportNamespace(node: N.ExportNamedDeclaration): void {
-    this.expectPlugin("exportNamespaceFrom");
-
-    const specifier = this.startNodeAt(
-      this.state.lastTokStart,
-      this.state.lastTokStartLoc,
-    );
-
-    this.next();
-
-    specifier.exported = this.parseIdentifier(true);
-
-    node.specifiers = [this.finishNode(specifier, "ExportNamespaceSpecifier")];
-
-    this.parseExportSpecifiersMaybe(node);
-    this.parseExportFrom(node, true);
-  }
-
   shouldParseExportDeclaration(): boolean {
     if (this.match(tt.at)) {
       this.expectOnePlugin(["decorators", "decorators-legacy"]);
@@ -1662,9 +1757,9 @@ export default class StatementParser extends ExpressionParser {
     return (
       this.state.type.keyword === "var" ||
       this.state.type.keyword === "const" ||
-      this.state.type.keyword === "let" ||
       this.state.type.keyword === "function" ||
       this.state.type.keyword === "class" ||
+      this.isLet() ||
       this.isAsyncFunction()
     );
   }
@@ -1741,27 +1836,24 @@ export default class StatementParser extends ExpressionParser {
   }
 
   checkDuplicateExports(
-    node: N.Identifier | N.ExportNamedDeclaration | N.ExportSpecifier,
+    node:
+      | N.Identifier
+      | N.ExportNamedDeclaration
+      | N.ExportSpecifier
+      | N.ExportDefaultSpecifier,
     name: string,
   ): void {
     if (this.state.exportedIdentifiers.indexOf(name) > -1) {
-      this.raiseDuplicateExportError(node, name);
+      throw this.raise(
+        node.start,
+        name === "default"
+          ? "Only one default export allowed per module."
+          : `\`${name}\` has already been exported. Exported identifiers must be unique.`,
+      );
     }
     this.state.exportedIdentifiers.push(name);
   }
 
-  raiseDuplicateExportError(
-    node: N.Identifier | N.ExportNamedDeclaration | N.ExportSpecifier,
-    name: string,
-  ): empty {
-    throw this.raise(
-      node.start,
-      name === "default"
-        ? "Only one default export allowed per module."
-        : `\`${name}\` has already been exported. Exported identifiers must be unique.`,
-    );
-  }
-
   // Parses a comma-separated list of module exports.
 
   parseExportSpecifiers(): Array<N.ExportSpecifier> {
@@ -1801,23 +1893,26 @@ export default class StatementParser extends ExpressionParser {
 
   // Parses import declaration.
 
-  parseImport(node: N.Node): N.ImportDeclaration | N.TsImportEqualsDeclaration {
+  parseImport(node: N.Node): N.AnyImport {
     // import '...'
-    if (this.match(tt.string)) {
-      node.specifiers = [];
-      node.source = this.parseExprAtom();
-    } else {
-      node.specifiers = [];
-      this.parseImportSpecifiers(node);
+    node.specifiers = [];
+    if (!this.match(tt.string)) {
+      const hasDefault = this.maybeParseDefaultImportSpecifier(node);
+      const parseNext = !hasDefault || this.eat(tt.comma);
+      const hasStar = parseNext && this.maybeParseStarImportSpecifier(node);
+      if (parseNext && !hasStar) this.parseNamedImportSpecifiers(node);
       this.expectContextual("from");
-      node.source = this.match(tt.string)
-        ? this.parseExprAtom()
-        : this.unexpected();
     }
+    node.source = this.parseImportSource();
     this.semicolon();
     return this.finishNode(node, "ImportDeclaration");
   }
 
+  parseImportSource(): N.StringLiteral {
+    if (!this.match(tt.string)) this.unexpected();
+    return this.parseExprAtom();
+  }
+
   // eslint-disable-next-line no-unused-vars
   shouldParseDefaultImport(node: N.ImportDeclaration): boolean {
     return this.match(tt.name);
@@ -1834,9 +1929,7 @@ export default class StatementParser extends ExpressionParser {
     node.specifiers.push(this.finishNode(specifier, type));
   }
 
-  // Parses a comma-separated list of module imports.
-  parseImportSpecifiers(node: N.ImportDeclaration): void {
-    let first = true;
+  maybeParseDefaultImportSpecifier(node: N.ImportDeclaration): boolean {
     if (this.shouldParseDefaultImport(node)) {
       // import defaultObj, { x, y as z } from '...'
       this.parseImportSpecifierLocal(
@@ -1845,10 +1938,12 @@ export default class StatementParser extends ExpressionParser {
         "ImportDefaultSpecifier",
         "default import specifier",
       );
-
-      if (!this.eat(tt.comma)) return;
+      return true;
     }
+    return false;
+  }
 
+  maybeParseStarImportSpecifier(node: N.ImportDeclaration): boolean {
     if (this.match(tt.star)) {
       const specifier = this.startNode();
       this.next();
@@ -1860,10 +1955,13 @@ export default class StatementParser extends ExpressionParser {
         "ImportNamespaceSpecifier",
         "import namespace specifier",
       );
-
-      return;
+      return true;
     }
+    return false;
+  }
 
+  parseNamedImportSpecifiers(node: N.ImportDeclaration) {
+    let first = true;
     this.expect(tt.braceL);
     while (!this.eat(tt.braceR)) {
       if (first) {

packages/babel-parser/src/parser/util.js

@@ -25,7 +25,7 @@ export default class UtilParser extends Tokenizer {
 
   isLookaheadRelational(op: "<" | ">"): boolean {
     const l = this.lookahead();
-    return l.type == tt.relational && l.value == op;
+    return l.type === tt.relational && l.value === op;
   }
 
   // TODO
@@ -87,7 +87,7 @@ export default class UtilParser extends Tokenizer {
 
   hasPrecedingLineBreak(): boolean {
     return lineBreak.test(
-      this.input.slice(this.state.lastTokEnd, this.state.start),
+      this.state.input.slice(this.state.lastTokEnd, this.state.start),
     );
   }
 
@@ -147,4 +147,22 @@ export default class UtilParser extends Tokenizer {
       );
     }
   }
+
+  checkYieldAwaitInDefaultParams() {
+    if (
+      this.state.yieldPos &&
+      (!this.state.awaitPos || this.state.yieldPos < this.state.awaitPos)
+    ) {
+      this.raise(
+        this.state.yieldPos,
+        "Yield cannot be used as name inside a generator function",
+      );
+    }
+    if (this.state.awaitPos) {
+      this.raise(
+        this.state.awaitPos,
+        "Await cannot be used as name inside an async function",
+      );
+    }
+  }
 }

packages/babel-parser/src/plugins/estree.js

@@ -300,7 +300,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
       if (node) {
         node.type = "Property";
-        if (node.kind === "method") node.kind = "init";
+        if (((node: any): N.ClassMethod).kind === "method") node.kind = "init";
         node.shorthand = false;
       }
 

packages/babel-parser/src/plugins/flow.js

@@ -344,7 +344,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       } else {
         if (
           this.match(tt._const) ||
-          this.match(tt._let) ||
+          this.isLet() ||
           ((this.isContextual("type") || this.isContextual("interface")) &&
             !insideModule)
         ) {
@@ -1124,7 +1124,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       node.types = [];
       this.expect(tt.bracketL);
       // We allow trailing commas
-      while (this.state.pos < this.input.length && !this.match(tt.bracketR)) {
+      while (this.state.pos < this.state.length && !this.match(tt.bracketR)) {
         node.types.push(this.flowParseType());
         if (this.match(tt.bracketR)) break;
         this.expect(tt.comma);
@@ -1190,9 +1190,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         case "any":
           return this.finishNode(node, "AnyTypeAnnotation");
 
-        case "void":
-          return this.finishNode(node, "VoidTypeAnnotation");
-
         case "bool":
         case "boolean":
           return this.finishNode(node, "BooleanTypeAnnotation");
@@ -1369,6 +1366,10 @@ export default (superClass: Class<Parser>): Class<Parser> =>
             "NumberLiteralTypeAnnotation",
           );
 
+        case tt._void:
+          this.next();
+          return this.finishNode(node, "VoidTypeAnnotation");
+
         case tt._null:
           this.next();
           return this.finishNode(node, "NullLiteralTypeAnnotation");
@@ -1384,6 +1385,10 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         default:
           if (this.state.type.keyword === "typeof") {
             return this.flowParseTypeofType();
+          } else if (this.state.type.keyword) {
+            const label = this.state.type.label;
+            this.next();
+            return super.createIdentifier(node, label);
           }
       }
 
@@ -1394,7 +1399,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       const startPos = this.state.start,
         startLoc = this.state.startLoc;
       let type = this.flowParsePrimaryType();
-      while (!this.canInsertSemicolon() && this.match(tt.bracketL)) {
+      while (this.match(tt.bracketL) && !this.canInsertSemicolon()) {
         const node = this.startNodeAt(startPos, startLoc);
         node.elementType = type;
         this.expect(tt.bracketL);
@@ -1561,7 +1566,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // interfaces
-    parseStatement(declaration: boolean, topLevel?: boolean): N.Statement {
+    parseStatement(context: ?string, topLevel?: boolean): N.Statement {
       // strict mode handling of `interface` since it's a reserved word
       if (
         this.state.strict &&
@@ -1572,7 +1577,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         this.next();
         return this.flowParseInterface(node);
       } else {
-        const stmt = super.parseStatement(declaration, topLevel);
+        const stmt = super.parseStatement(context, topLevel);
         // We will parse a flow pragma in any comment before the first statement.
         if (this.flowPragma === undefined && !this.isValidDirective(stmt)) {
           this.flowPragma = null;
@@ -1626,7 +1631,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         this.match(tt.name) &&
         (this.state.value === "type" ||
           this.state.value === "interface" ||
-          this.state.value == "opaque")
+          this.state.value === "opaque")
       ) {
         return false;
       }
@@ -1842,15 +1847,15 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       super.assertModuleNodeAllowed(node);
     }
 
-    parseExport(node: N.ExportNamedDeclaration): N.ExportNamedDeclaration {
-      node = super.parseExport(node);
+    parseExport(node: N.Node): N.AnyExport {
+      const decl = super.parseExport(node);
       if (
-        node.type === "ExportNamedDeclaration" ||
-        node.type === "ExportAllDeclaration"
+        decl.type === "ExportNamedDeclaration" ||
+        decl.type === "ExportAllDeclaration"
       ) {
-        node.exportKind = node.exportKind || "value";
+        decl.exportKind = decl.exportKind || "value";
       }
-      return node;
+      return decl;
     }
 
     parseExportDeclaration(node: N.ExportNamedDeclaration): ?N.Declaration {
@@ -1886,27 +1891,26 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
     }
 
-    shouldParseExportStar(): boolean {
-      return (
-        super.shouldParseExportStar() ||
-        (this.isContextual("type") && this.lookahead().type === tt.star)
-      );
-    }
+    eatExportStar(node: N.Node): boolean {
+      if (super.eatExportStar(...arguments)) return true;
 
-    parseExportStar(node: N.ExportNamedDeclaration): void {
-      if (this.eatContextual("type")) {
+      if (this.isContextual("type") && this.lookahead().type === tt.star) {
         node.exportKind = "type";
+        this.next();
+        this.next();
+        return true;
       }
 
-      return super.parseExportStar(node);
+      return false;
     }
 
-    parseExportNamespace(node: N.ExportNamedDeclaration) {
-      if (node.exportKind === "type") {
-        this.unexpected();
+    maybeParseExportNamespaceSpecifier(node: N.Node): boolean {
+      const pos = this.state.start;
+      const hasNamespace = super.maybeParseExportNamespaceSpecifier(node);
+      if (hasNamespace && node.exportKind === "type") {
+        this.unexpected(pos);
       }
-
-      return super.parseExportNamespace(node);
+      return hasNamespace;
     }
 
     parseClassId(node: N.Class, isStatement: boolean, optionalId: ?boolean) {
@@ -1916,20 +1920,12 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
     }
 
-    // don't consider `void` to be a keyword as then it'll use the void token type
-    // and set startExpr
-    isKeyword(name: string): boolean {
-      if (this.state.inType && name === "void") {
-        return false;
-      } else {
-        return super.isKeyword(name);
-      }
-    }
-
     // ensure that inside flow types, we bypass the jsx parser plugin
-    readToken(code: number): void {
-      const next = this.input.charCodeAt(this.state.pos + 1);
-      if (
+    getTokenFromCode(code: number): void {
+      const next = this.state.input.charCodeAt(this.state.pos + 1);
+      if (code === charCodes.leftCurlyBrace && next === charCodes.verticalBar) {
+        return this.finishOp(tt.braceBarL, 2);
+      } else if (
         this.state.inType &&
         (code === charCodes.greaterThan || code === charCodes.lessThan)
       ) {
@@ -1938,7 +1934,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         this.state.isIterator = true;
         return super.readWord();
       } else {
-        return super.readToken(code);
+        return super.getTokenFromCode(code);
       }
     }
 
@@ -2226,7 +2222,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // parse typeof and type imports
-    parseImportSpecifiers(node: N.ImportDeclaration): void {
+    maybeParseDefaultImportSpecifier(node: N.ImportDeclaration): boolean {
       node.importKind = "value";
 
       let kind = null;
@@ -2253,7 +2249,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         }
       }
 
-      super.parseImportSpecifiers(node);
+      return super.maybeParseDefaultImportSpecifier(node);
     }
 
     // parse import-type/typeof shorthand
@@ -2348,8 +2344,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // parse flow type annotations on variable declarator heads - let foo: string = bar
-    parseVarHead(decl: N.VariableDeclarator): void {
-      super.parseVarHead(decl);
+    parseVarId(
+      decl: N.VariableDeclarator,
+      kind: "var" | "let" | "const",
+    ): void {
+      super.parseVarId(decl, kind);
       if (this.match(tt.colon)) {
         decl.id.typeAnnotation = this.flowParseTypeAnnotation();
         this.finishNode(decl.id, decl.id.type);
@@ -2680,7 +2679,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     readToken_mult_modulo(code: number): void {
-      const next = this.input.charCodeAt(this.state.pos + 1);
+      const next = this.state.input.charCodeAt(this.state.pos + 1);
       if (
         code === charCodes.asterisk &&
         next === charCodes.slash &&
@@ -2695,21 +2694,44 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       super.readToken_mult_modulo(code);
     }
 
-    skipBlockComment(): void {
+    readToken_pipe_amp(code: number): void {
+      const next = this.state.input.charCodeAt(this.state.pos + 1);
       if (
-        this.hasPlugin("flow") &&
-        this.hasPlugin("flowComments") &&
-        this.skipFlowComment()
+        code === charCodes.verticalBar &&
+        next === charCodes.rightCurlyBrace
       ) {
+        // '|}'
+        this.finishOp(tt.braceBarR, 2);
+        return;
+      }
+
+      super.readToken_pipe_amp(code);
+    }
+
+    parseTopLevel(file: N.File, program: N.Program): N.File {
+      const fileNode = super.parseTopLevel(file, program);
+      if (this.state.hasFlowComment) {
+        this.unexpected(null, "Unterminated flow-comment");
+      }
+      return fileNode;
+    }
+
+    skipBlockComment(): void {
+      if (this.hasPlugin("flowComments") && this.skipFlowComment()) {
+        if (this.state.hasFlowComment) {
+          this.unexpected(
+            null,
+            "Cannot have a flow comment inside another flow comment",
+          );
+        }
         this.hasFlowCommentCompletion();
         this.state.pos += this.skipFlowComment();
         this.state.hasFlowComment = true;
         return;
       }
 
-      let end;
-      if (this.hasPlugin("flow") && this.state.hasFlowComment) {
-        end = this.input.indexOf("*-/", (this.state.pos += 2));
+      if (this.state.hasFlowComment) {
+        const end = this.state.input.indexOf("*-/", (this.state.pos += 2));
         if (end === -1) this.raise(this.state.pos - 2, "Unterminated comment");
         this.state.pos = end + 3;
         return;
@@ -2719,23 +2741,40 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     skipFlowComment(): number | boolean {
-      const ch2 = this.input.charCodeAt(this.state.pos + 2);
-      const ch3 = this.input.charCodeAt(this.state.pos + 3);
+      const { pos } = this.state;
+      let shiftToFirstNonWhiteSpace = 2;
+      while (
+        [charCodes.space, charCodes.tab].includes(
+          this.state.input.charCodeAt(pos + shiftToFirstNonWhiteSpace),
+        )
+      ) {
+        shiftToFirstNonWhiteSpace++;
+      }
+
+      const ch2 = this.state.input.charCodeAt(shiftToFirstNonWhiteSpace + pos);
+      const ch3 = this.state.input.charCodeAt(
+        shiftToFirstNonWhiteSpace + pos + 1,
+      );
 
       if (ch2 === charCodes.colon && ch3 === charCodes.colon) {
-        return 4; // check for /*::
+        return shiftToFirstNonWhiteSpace + 2; // check for /*::
       }
-      if (this.input.slice(this.state.pos + 2, 14) === "flow-include") {
-        return 14; // check for /*flow-include
+      if (
+        this.state.input.slice(
+          shiftToFirstNonWhiteSpace + pos,
+          shiftToFirstNonWhiteSpace + pos + 12,
+        ) === "flow-include"
+      ) {
+        return shiftToFirstNonWhiteSpace + 12; // check for /*flow-include
       }
       if (ch2 === charCodes.colon && ch3 !== charCodes.colon) {
-        return 2; // check for /*:, advance only 2 steps
+        return shiftToFirstNonWhiteSpace; // check for /*:, advance up to :
       }
       return false;
     }
 
     hasFlowCommentCompletion(): void {
-      const end = this.input.indexOf("*/", this.state.pos);
+      const end = this.state.input.indexOf("*/", this.state.pos);
       if (end === -1) {
         this.raise(this.state.pos, "Unterminated comment");
       }

packages/babel-parser/src/plugins/jsx/index.js

@@ -79,11 +79,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       let out = "";
       let chunkStart = this.state.pos;
       for (;;) {
-        if (this.state.pos >= this.input.length) {
+        if (this.state.pos >= this.state.length) {
           this.raise(this.state.start, "Unterminated JSX contents");
         }
 
-        const ch = this.input.charCodeAt(this.state.pos);
+        const ch = this.state.input.charCodeAt(this.state.pos);
 
         switch (ch) {
           case charCodes.lessThan:
@@ -93,20 +93,20 @@ export default (superClass: Class<Parser>): Class<Parser> =>
                 ++this.state.pos;
                 return this.finishToken(tt.jsxTagStart);
               }
-              return this.getTokenFromCode(ch);
+              return super.getTokenFromCode(ch);
             }
-            out += this.input.slice(chunkStart, this.state.pos);
+            out += this.state.input.slice(chunkStart, this.state.pos);
             return this.finishToken(tt.jsxText, out);
 
           case charCodes.ampersand:
-            out += this.input.slice(chunkStart, this.state.pos);
+            out += this.state.input.slice(chunkStart, this.state.pos);
             out += this.jsxReadEntity();
             chunkStart = this.state.pos;
             break;
 
           default:
             if (isNewLine(ch)) {
-              out += this.input.slice(chunkStart, this.state.pos);
+              out += this.state.input.slice(chunkStart, this.state.pos);
               out += this.jsxReadNewLine(true);
               chunkStart = this.state.pos;
             } else {
@@ -117,12 +117,12 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     jsxReadNewLine(normalizeCRLF: boolean): string {
-      const ch = this.input.charCodeAt(this.state.pos);
+      const ch = this.state.input.charCodeAt(this.state.pos);
       let out;
       ++this.state.pos;
       if (
         ch === charCodes.carriageReturn &&
-        this.input.charCodeAt(this.state.pos) === charCodes.lineFeed
+        this.state.input.charCodeAt(this.state.pos) === charCodes.lineFeed
       ) {
         ++this.state.pos;
         out = normalizeCRLF ? "\n" : "\r\n";
@@ -139,25 +139,25 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       let out = "";
       let chunkStart = ++this.state.pos;
       for (;;) {
-        if (this.state.pos >= this.input.length) {
+        if (this.state.pos >= this.state.length) {
           this.raise(this.state.start, "Unterminated string constant");
         }
 
-        const ch = this.input.charCodeAt(this.state.pos);
+        const ch = this.state.input.charCodeAt(this.state.pos);
         if (ch === quote) break;
         if (ch === charCodes.ampersand) {
-          out += this.input.slice(chunkStart, this.state.pos);
+          out += this.state.input.slice(chunkStart, this.state.pos);
           out += this.jsxReadEntity();
           chunkStart = this.state.pos;
         } else if (isNewLine(ch)) {
-          out += this.input.slice(chunkStart, this.state.pos);
+          out += this.state.input.slice(chunkStart, this.state.pos);
           out += this.jsxReadNewLine(false);
           chunkStart = this.state.pos;
         } else {
           ++this.state.pos;
         }
       }
-      out += this.input.slice(chunkStart, this.state.pos++);
+      out += this.state.input.slice(chunkStart, this.state.pos++);
       return this.finishToken(tt.string, out);
     }
 
@@ -165,11 +165,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       let str = "";
       let count = 0;
       let entity;
-      let ch = this.input[this.state.pos];
+      let ch = this.state.input[this.state.pos];
 
       const startPos = ++this.state.pos;
-      while (this.state.pos < this.input.length && count++ < 10) {
-        ch = this.input[this.state.pos++];
+      while (this.state.pos < this.state.length && count++ < 10) {
+        ch = this.state.input[this.state.pos++];
         if (ch === ";") {
           if (str[0] === "#") {
             if (str[1] === "x") {
@@ -208,11 +208,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       let ch;
       const start = this.state.pos;
       do {
-        ch = this.input.charCodeAt(++this.state.pos);
+        ch = this.state.input.charCodeAt(++this.state.pos);
       } while (isIdentifierChar(ch) || ch === charCodes.dash);
       return this.finishToken(
         tt.jsxName,
-        this.input.slice(start, this.state.pos),
+        this.state.input.slice(start, this.state.pos),
       );
     }
 
@@ -520,8 +520,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
     }
 
-    readToken(code: number): void {
-      if (this.state.inPropertyName) return super.readToken(code);
+    getTokenFromCode(code: number): void {
+      if (this.state.inPropertyName) return super.getTokenFromCode(code);
 
       const context = this.curContext();
 
@@ -557,7 +557,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         return this.finishToken(tt.jsxTagStart);
       }
 
-      return super.readToken(code);
+      return super.getTokenFromCode(code);
     }
 
     updateContext(prevType: TokenType): void {

packages/babel-parser/src/plugins/typescript.js

@@ -45,6 +45,8 @@ function keywordTypeFromName(
       return "TSAnyKeyword";
     case "boolean":
       return "TSBooleanKeyword";
+    case "bigint":
+      return "TSBigIntKeyword";
     case "never":
       return "TSNeverKeyword";
     case "number":
@@ -218,6 +220,28 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return result;
     }
 
+    tsParseImportType(): N.TsImportType {
+      const node: N.TsImportType = this.startNode();
+      this.expect(tt._import);
+      this.expect(tt.parenL);
+      if (!this.match(tt.string)) {
+        throw this.unexpected(
+          null,
+          "Argument in a type import must be a string literal",
+        );
+      }
+      node.argument = this.parseLiteral(this.state.value, "StringLiteral");
+      this.expect(tt.parenR);
+
+      if (this.eat(tt.dot)) {
+        node.qualifier = this.tsParseEntityName(/* allowReservedWords */ true);
+      }
+      if (this.isRelational("<")) {
+        node.typeParameters = this.tsParseTypeArguments();
+      }
+      return this.finishNode(node, "TSImportType");
+    }
+
     tsParseEntityName(allowReservedWords: boolean): N.TsEntityName {
       let entity: N.TsEntityName = this.parseIdentifier();
       while (this.eat(tt.dot)) {
@@ -240,7 +264,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
     tsParseThisTypePredicate(lhs: N.TsThisType): N.TsTypePredicate {
       this.next();
-      const node: N.TsTypePredicate = this.startNode();
+      const node: N.TsTypePredicate = this.startNodeAtNode(lhs);
       node.parameterName = lhs;
       node.typeAnnotation = this.tsParseTypeAnnotation(/* eatColon */ false);
       return this.finishNode(node, "TSTypePredicate");
@@ -255,7 +279,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     tsParseTypeQuery(): N.TsTypeQuery {
       const node: N.TsTypeQuery = this.startNode();
       this.expect(tt._typeof);
-      node.exprName = this.tsParseEntityName(/* allowReservedWords */ true);
+      if (this.match(tt._import)) {
+        node.exprName = this.tsParseImportType();
+      } else {
+        node.exprName = this.tsParseEntityName(/* allowReservedWords */ true);
+      }
       return this.finishNode(node, "TSTypeQuery");
     }
 
@@ -314,17 +342,18 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     tsParseBindingListForSignature(): $ReadOnlyArray<
-      N.Identifier | N.RestElement | N.ObjectPattern,
+      N.Identifier | N.RestElement | N.ObjectPattern | N.ArrayPattern,
     > {
       return this.parseBindingList(tt.parenR).map(pattern => {
         if (
           pattern.type !== "Identifier" &&
           pattern.type !== "RestElement" &&
-          pattern.type !== "ObjectPattern"
+          pattern.type !== "ObjectPattern" &&
+          pattern.type !== "ArrayPattern"
         ) {
           throw this.unexpected(
             pattern.start,
-            `Name in a signature must be an Identifier or ObjectPattern, instead got ${
+            `Name in a signature must be an Identifier, ObjectPattern or ArrayPattern, instead got ${
               pattern.type
             }`,
           );
@@ -370,8 +399,9 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
       this.expect(tt.bracketL);
       const id = this.parseIdentifier();
-      this.expect(tt.colon);
-      id.typeAnnotation = this.tsParseTypeAnnotation(/* eatColon */ false);
+      id.typeAnnotation = this.tsParseTypeAnnotation();
+      this.finishNode(id, "Identifier"); // set end position to end of type
+
       this.expect(tt.bracketR);
       node.parameters = [id];
 
@@ -518,17 +548,10 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       //   No mandatory elements may follow optional elements
       //   If there's a rest element, it must be at the end of the tuple
       let seenOptionalElement = false;
-      node.elementTypes.forEach((elementNode, i) => {
-        if (elementNode.type === "TSRestType") {
-          if (i !== node.elementTypes.length - 1) {
-            this.raise(
-              elementNode.start,
-              "A rest element must be last in a tuple type.",
-            );
-          }
-        } else if (elementNode.type === "TSOptionalType") {
+      node.elementTypes.forEach(elementNode => {
+        if (elementNode.type === "TSOptionalType") {
           seenOptionalElement = true;
-        } else if (seenOptionalElement) {
+        } else if (seenOptionalElement && elementNode.type !== "TSRestType") {
           this.raise(
             elementNode.start,
             "A required element cannot follow an optional element.",
@@ -545,6 +568,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         const restNode: N.TsRestType = this.startNode();
         this.next(); // skips ellipsis
         restNode.typeAnnotation = this.tsParseType();
+        this.checkCommaAfterRest(tt.bracketR, "type");
         return this.finishNode(restNode, "TSRestType");
       }
 
@@ -643,6 +667,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         }
         case tt._typeof:
           return this.tsParseTypeQuery();
+        case tt._import:
+          return this.tsParseImportType();
         case tt.braceL:
           return this.tsLookAhead(this.tsIsStartOfMappedType.bind(this))
             ? this.tsParseMappedType()
@@ -769,6 +795,21 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         return true;
       }
 
+      if (this.match(tt.bracketL)) {
+        let braceStackCounter = 1;
+        this.next();
+
+        while (braceStackCounter > 0) {
+          if (this.match(tt.bracketL)) {
+            ++braceStackCounter;
+          } else if (this.match(tt.bracketR)) {
+            --braceStackCounter;
+          }
+          this.next();
+        }
+        return true;
+      }
+
       return false;
     }
 
@@ -894,6 +935,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
     tsParseTypeAssertion(): N.TsTypeAssertion {
       const node: N.TsTypeAssertion = this.startNode();
+      this.next(); // <
       // Not actually necessary to set state.inType because we never reach here if JSX plugin is enabled,
       // but need `tsInType` to satisfy the assertion in `tsParseType`.
       node.typeAnnotation = this.tsInType(() => this.tsParseType());
@@ -902,11 +944,21 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return this.finishNode(node, "TSTypeAssertion");
     }
 
-    tsParseHeritageClause(): $ReadOnlyArray<N.TsExpressionWithTypeArguments> {
-      return this.tsParseDelimitedList(
+    tsParseHeritageClause(
+      descriptor: string,
+    ): $ReadOnlyArray<N.TsExpressionWithTypeArguments> {
+      const originalStart = this.state.start;
+
+      const delimitedList = this.tsParseDelimitedList(
         "HeritageClauseElement",
         this.tsParseExpressionWithTypeArguments.bind(this),
       );
+
+      if (!delimitedList.length) {
+        this.raise(originalStart, `'${descriptor}' list cannot be empty.`);
+      }
+
+      return delimitedList;
     }
 
     tsParseExpressionWithTypeArguments(): N.TsExpressionWithTypeArguments {
@@ -927,7 +979,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       node.id = this.parseIdentifier();
       node.typeParameters = this.tsTryParseTypeParameters();
       if (this.eat(tt._extends)) {
-        node.extends = this.tsParseHeritageClause();
+        node.extends = this.tsParseHeritageClause("extends");
       }
       const body: N.TSInterfaceBody = this.startNode();
       body.body = this.tsInType(this.tsParseObjectTypeMembers.bind(this));
@@ -1151,7 +1203,18 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     tsTryParseDeclare(nany: any): ?N.Declaration {
-      switch (this.state.type) {
+      if (this.isLineTerminator()) {
+        return;
+      }
+      let starttype = this.state.type;
+      let kind;
+
+      if (this.isContextual("let")) {
+        starttype = tt._var;
+        kind = "let";
+      }
+
+      switch (starttype) {
         case tt._function:
           this.next();
           return this.parseFunction(nany, /* isStatement */ true);
@@ -1170,8 +1233,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
           }
         // falls through
         case tt._var:
-        case tt._let:
-          return this.parseVarStatement(nany, this.state.type);
+          kind = kind || this.state.value;
+          return this.parseVarStatement(nany, kind);
         case tt.name: {
           const value = this.state.value;
           if (value === "global") {
@@ -1227,10 +1290,15 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     ): ?N.Declaration {
       switch (value) {
         case "abstract":
-          if (next || this.match(tt._class)) {
+          if (this.tsCheckLineTerminatorAndMatch(tt._class, next)) {
             const cls: N.ClassDeclaration = node;
             cls.abstract = true;
-            if (next) this.next();
+            if (next) {
+              this.next();
+              if (!this.match(tt._class)) {
+                this.unexpected(null, tt._class);
+              }
+            }
             return this.parseClass(
               cls,
               /* isStatement */ true,
@@ -1247,7 +1315,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
           break;
 
         case "interface":
-          if (next || this.match(tt.name)) {
+          if (this.tsCheckLineTerminatorAndMatch(tt.name, next)) {
             if (next) this.next();
             return this.tsParseInterfaceDeclaration(node);
           }
@@ -1257,20 +1325,20 @@ export default (superClass: Class<Parser>): Class<Parser> =>
           if (next) this.next();
           if (this.match(tt.string)) {
             return this.tsParseAmbientExternalModuleDeclaration(node);
-          } else if (next || this.match(tt.name)) {
+          } else if (this.tsCheckLineTerminatorAndMatch(tt.name, next)) {
             return this.tsParseModuleOrNamespaceDeclaration(node);
           }
           break;
 
         case "namespace":
-          if (next || this.match(tt.name)) {
+          if (this.tsCheckLineTerminatorAndMatch(tt.name, next)) {
             if (next) this.next();
             return this.tsParseModuleOrNamespaceDeclaration(node);
           }
           break;
 
         case "type":
-          if (next || this.match(tt.name)) {
+          if (this.tsCheckLineTerminatorAndMatch(tt.name, next)) {
             if (next) this.next();
             return this.tsParseTypeAliasDeclaration(node);
           }
@@ -1278,6 +1346,10 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
     }
 
+    tsCheckLineTerminatorAndMatch(tokenType: TokenType, next: boolean) {
+      return (next || this.match(tokenType)) && !this.isLineTerminator();
+    }
+
     tsTryParseGenericAsyncArrowFunction(
       startPos: number,
       startLoc: Position,
@@ -1362,6 +1434,10 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       allowModifiers: ?boolean,
       decorators: N.Decorator[],
     ): N.Pattern | N.TSParameterProperty {
+      // Store original location/position to include modifiers in range
+      const startPos = this.state.start;
+      const startLoc = this.state.startLoc;
+
       let accessibility: ?N.Accessibility;
       let readonly = false;
       if (allowModifiers) {
@@ -1373,7 +1449,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       this.parseAssignableListItemTypes(left);
       const elt = this.parseMaybeDefault(left.start, left.loc.start, left);
       if (accessibility || readonly) {
-        const pp: N.TSParameterProperty = this.startNodeAtNode(elt);
+        const pp: N.TSParameterProperty = this.startNodeAt(startPos, startLoc);
         if (decorators.length) {
           pp.decorators = decorators;
         }
@@ -1387,12 +1463,13 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         }
         pp.parameter = elt;
         return this.finishNode(pp, "TSParameterProperty");
-      } else {
-        if (decorators.length) {
-          left.decorators = decorators;
-        }
-        return elt;
       }
+
+      if (decorators.length) {
+        left.decorators = decorators;
+      }
+
+      return elt;
     }
 
     parseFunctionBodyAndFinish(
@@ -1561,16 +1638,14 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     */
     checkDuplicateExports() {}
 
-    parseImport(
-      node: N.Node,
-    ): N.ImportDeclaration | N.TsImportEqualsDeclaration {
+    parseImport(node: N.Node): N.AnyImport {
       if (this.match(tt.name) && this.lookahead().type === tt.eq) {
         return this.tsParseImportEqualsDeclaration(node);
       }
       return super.parseImport(node);
     }
 
-    parseExport(node: N.Node): N.Node {
+    parseExport(node: N.Node): N.AnyExport {
       if (this.match(tt._import)) {
         // `export import A = B;`
         this.expect(tt._import);
@@ -1624,10 +1699,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return super.parseExportDefaultExpression();
     }
 
-    parseStatementContent(
-      declaration: boolean,
-      topLevel: ?boolean,
-    ): N.Statement {
+    parseStatementContent(context: ?string, topLevel: ?boolean): N.Statement {
       if (this.state.type === tt._const) {
         const ahead = this.lookahead();
         if (ahead.type === tt.name && ahead.value === "enum") {
@@ -1637,7 +1709,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
           return this.tsParseEnumDeclaration(node, /* isConst */ true);
         }
       }
-      return super.parseStatementContent(declaration, topLevel);
+      return super.parseStatementContent(context, topLevel);
     }
 
     parseAccessModifier(): ?N.Accessibility {
@@ -1790,14 +1862,19 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         return this.finishNode(typeCastNode, "TSTypeCastExpression");
       }
 
-      return node;
+      return this.finishNode(node, node.type);
     }
 
     parseExportDeclaration(node: N.ExportNamedDeclaration): ?N.Declaration {
+      // Store original location/position
+      const startPos = this.state.start;
+      const startLoc = this.state.startLoc;
+
       // "export declare" is equivalent to just "export".
       const isDeclare = this.eatContextual("declare");
 
       let declaration: ?N.Declaration;
+
       if (this.match(tt.name)) {
         declaration = this.tsTryParseExportDeclaration();
       }
@@ -1806,6 +1883,9 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
 
       if (declaration && isDeclare) {
+        // Reset location to include `declare` in range
+        this.resetStartLocation(declaration, startPos, startLoc);
+
         declaration.declare = true;
       }
 
@@ -1871,7 +1951,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         node.superTypeParameters = this.tsParseTypeArguments();
       }
       if (this.eatContextual("implements")) {
-        node.implements = this.tsParseHeritageClause();
+        node.implements = this.tsParseHeritageClause("implements");
       }
     }
 
@@ -1889,8 +1969,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // `let x: number;`
-    parseVarHead(decl: N.VariableDeclarator): void {
-      super.parseVarHead(decl);
+    parseVarId(
+      decl: N.VariableDeclarator,
+      kind: "var" | "let" | "const",
+    ): void {
+      super.parseVarId(decl, kind);
       if (decl.id.type === "Identifier" && this.eat(tt.bang)) {
         decl.definite = true;
       }
@@ -1983,10 +2066,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
       // Correct TypeScript code should have at least 1 type parameter, but don't crash on bad code.
       if (typeParameters && typeParameters.params.length !== 0) {
-        this.resetStartLocationFromNode(
-          arrowExpression,
-          typeParameters.params[0],
-        );
+        this.resetStartLocationFromNode(arrowExpression, typeParameters);
       }
       arrowExpression.typeParameters = typeParameters;
       return arrowExpression;
@@ -1994,7 +2074,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
     // Handle type assertions
     parseMaybeUnary(refShorthandDefaultPos?: ?Pos): N.Expression {
-      if (!this.hasPlugin("jsx") && this.eatRelational("<")) {
+      if (!this.hasPlugin("jsx") && this.isRelational("<")) {
         return this.tsParseTypeAssertion();
       } else {
         return super.parseMaybeUnary(refShorthandDefaultPos);
@@ -2167,11 +2247,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     // ensure that inside types, we bypass the jsx parser plugin
-    readToken(code: number): void {
+    getTokenFromCode(code: number): void {
       if (this.state.inType && (code === 62 || code === 60)) {
         return this.finishOp(tt.relational, 1);
       } else {
-        return super.readToken(code);
+        return super.getTokenFromCode(code);
       }
     }
 

packages/babel-parser/src/tokenizer/context.js

@@ -107,7 +107,9 @@ tt._function.updateContext = tt._class.updateContext = function(prevType) {
     prevType !== tt._else &&
     !(
       prevType === tt._return &&
-      lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start))
+      lineBreak.test(
+        this.state.input.slice(this.state.lastTokEnd, this.state.start),
+      )
     ) &&
     !(
       (prevType === tt.colon || prevType === tt.braceL) &&

packages/babel-parser/src/tokenizer/index.js

@@ -3,11 +3,7 @@
 import type { Options } from "../options";
 import type { Position } from "../util/location";
 import * as charCodes from "charcodes";
-import {
-  isIdentifierStart,
-  isIdentifierChar,
-  isKeyword,
-} from "../util/identifier";
+import { isIdentifierStart, isIdentifierChar } from "../util/identifier";
 import { types as tt, keywords as keywordTypes, type TokenType } from "./types";
 import { type TokContext, types as ct } from "./context";
 import LocationParser from "../parser/location";
@@ -20,7 +16,7 @@ import {
 } from "../util/whitespace";
 import State from "./state";
 
-const VALID_REGEX_FLAGS = "gmsiyu";
+const VALID_REGEX_FLAGS = new Set(["g", "m", "s", "i", "y", "u"]);
 
 // The following character codes are forbidden from being
 // an immediate sibling of NumericLiteralSeparator _
@@ -157,12 +153,6 @@ export default class Tokenizer extends LocationParser {
 
   // TODO
 
-  isKeyword(word: string): boolean {
-    return isKeyword(word);
-  }
-
-  // TODO
-
   lookahead(): State {
     const old = this.state;
     this.state = old.clone(true);
@@ -185,7 +175,7 @@ export default class Tokenizer extends LocationParser {
     this.state.pos = this.state.start;
     while (this.state.pos < this.state.lineStart) {
       this.state.lineStart =
-        this.input.lastIndexOf("\n", this.state.lineStart - 2) + 1;
+        this.state.input.lastIndexOf("\n", this.state.lineStart - 2) + 1;
       --this.state.curLine;
     }
     this.nextToken();
@@ -206,7 +196,7 @@ export default class Tokenizer extends LocationParser {
     this.state.octalPosition = null;
     this.state.start = this.state.pos;
     this.state.startLoc = this.state.curPosition();
-    if (this.state.pos >= this.input.length) {
+    if (this.state.pos >= this.state.length) {
       this.finishToken(tt.eof);
       return;
     }
@@ -214,17 +204,7 @@ export default class Tokenizer extends LocationParser {
     if (curContext.override) {
       curContext.override(this);
     } else {
-      this.readToken(this.input.codePointAt(this.state.pos));
-    }
-  }
-
-  readToken(code: number): void {
-    // Identifier or keyword. '\uXXXX' sequences are allowed in
-    // identifiers, so '\' also dispatches to that.
-    if (isIdentifierStart(code) || code === charCodes.backslash) {
-      this.readWord();
-    } else {
-      this.getTokenFromCode(code);
+      this.getTokenFromCode(this.state.input.codePointAt(this.state.pos));
     }
   }
 
@@ -254,14 +234,14 @@ export default class Tokenizer extends LocationParser {
   skipBlockComment(): void {
     const startLoc = this.state.curPosition();
     const start = this.state.pos;
-    const end = this.input.indexOf("*/", (this.state.pos += 2));
+    const end = this.state.input.indexOf("*/", (this.state.pos += 2));
     if (end === -1) this.raise(this.state.pos - 2, "Unterminated comment");
 
     this.state.pos = end + 2;
     lineBreakG.lastIndex = start;
     let match;
     while (
-      (match = lineBreakG.exec(this.input)) &&
+      (match = lineBreakG.exec(this.state.input)) &&
       match.index < this.state.pos
     ) {
       ++this.state.curLine;
@@ -270,7 +250,7 @@ export default class Tokenizer extends LocationParser {
 
     this.pushComment(
       true,
-      this.input.slice(start + 2, end),
+      this.state.input.slice(start + 2, end),
       start,
       this.state.pos,
       startLoc,
@@ -281,22 +261,22 @@ export default class Tokenizer extends LocationParser {
   skipLineComment(startSkip: number): void {
     const start = this.state.pos;
     const startLoc = this.state.curPosition();
-    let ch = this.input.charCodeAt((this.state.pos += startSkip));
-    if (this.state.pos < this.input.length) {
+    let ch = this.state.input.charCodeAt((this.state.pos += startSkip));
+    if (this.state.pos < this.state.length) {
       while (
         ch !== charCodes.lineFeed &&
         ch !== charCodes.carriageReturn &&
         ch !== charCodes.lineSeparator &&
         ch !== charCodes.paragraphSeparator &&
-        ++this.state.pos < this.input.length
+        ++this.state.pos < this.state.length
       ) {
-        ch = this.input.charCodeAt(this.state.pos);
+        ch = this.state.input.charCodeAt(this.state.pos);
       }
     }
 
     this.pushComment(
       false,
-      this.input.slice(start + startSkip, this.state.pos),
+      this.state.input.slice(start + startSkip, this.state.pos),
       start,
       this.state.pos,
       startLoc,
@@ -308,12 +288,18 @@ export default class Tokenizer extends LocationParser {
   // whitespace and comments, and.
 
   skipSpace(): void {
-    loop: while (this.state.pos < this.input.length) {
-      const ch = this.input.charCodeAt(this.state.pos);
+    loop: while (this.state.pos < this.state.length) {
+      const ch = this.state.input.charCodeAt(this.state.pos);
       switch (ch) {
+        case charCodes.space:
+        case charCodes.nonBreakingSpace:
+        case charCodes.tab:
+          ++this.state.pos;
+          break;
         case charCodes.carriageReturn:
           if (
-            this.input.charCodeAt(this.state.pos + 1) === charCodes.lineFeed
+            this.state.input.charCodeAt(this.state.pos + 1) ===
+            charCodes.lineFeed
           ) {
             ++this.state.pos;
           }
@@ -327,7 +313,7 @@ export default class Tokenizer extends LocationParser {
           break;
 
         case charCodes.slash:
-          switch (this.input.charCodeAt(this.state.pos + 1)) {
+          switch (this.state.input.charCodeAt(this.state.pos + 1)) {
             case charCodes.asterisk:
               this.skipBlockComment();
               break;
@@ -382,7 +368,7 @@ export default class Tokenizer extends LocationParser {
     }
 
     const nextPos = this.state.pos + 1;
-    const next = this.input.charCodeAt(nextPos);
+    const next = this.state.input.charCodeAt(nextPos);
     if (next >= charCodes.digit0 && next <= charCodes.digit9) {
       this.raise(this.state.pos, "Unexpected digit after hash token");
     }
@@ -405,13 +391,13 @@ export default class Tokenizer extends LocationParser {
   }
 
   readToken_dot(): void {
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
     if (next >= charCodes.digit0 && next <= charCodes.digit9) {
       this.readNumber(true);
       return;
     }
 
-    const next2 = this.input.charCodeAt(this.state.pos + 2);
+    const next2 = this.state.input.charCodeAt(this.state.pos + 2);
     if (next === charCodes.dot && next2 === charCodes.dot) {
       this.state.pos += 3;
       this.finishToken(tt.ellipsis);
@@ -429,7 +415,7 @@ export default class Tokenizer extends LocationParser {
       return;
     }
 
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
     if (next === charCodes.equalsTo) {
       this.finishOp(tt.assign, 2);
     } else {
@@ -438,12 +424,12 @@ export default class Tokenizer extends LocationParser {
   }
 
   readToken_interpreter(): boolean {
-    if (this.state.pos !== 0 || this.state.input.length < 2) return false;
+    if (this.state.pos !== 0 || this.state.length < 2) return false;
 
     const start = this.state.pos;
     this.state.pos += 1;
 
-    let ch = this.input.charCodeAt(this.state.pos);
+    let ch = this.state.input.charCodeAt(this.state.pos);
     if (ch !== charCodes.exclamationMark) return false;
 
     while (
@@ -451,12 +437,12 @@ export default class Tokenizer extends LocationParser {
       ch !== charCodes.carriageReturn &&
       ch !== charCodes.lineSeparator &&
       ch !== charCodes.paragraphSeparator &&
-      ++this.state.pos < this.input.length
+      ++this.state.pos < this.state.length
     ) {
-      ch = this.input.charCodeAt(this.state.pos);
+      ch = this.state.input.charCodeAt(this.state.pos);
     }
 
-    const value = this.input.slice(start + 2, this.state.pos);
+    const value = this.state.input.slice(start + 2, this.state.pos);
 
     this.finishToken(tt.interpreterDirective, value);
 
@@ -467,13 +453,13 @@ export default class Tokenizer extends LocationParser {
     // '%*'
     let type = code === charCodes.asterisk ? tt.star : tt.modulo;
     let width = 1;
-    let next = this.input.charCodeAt(this.state.pos + 1);
+    let next = this.state.input.charCodeAt(this.state.pos + 1);
     const exprAllowed = this.state.exprAllowed;
 
     // Exponentiation operator **
     if (code === charCodes.asterisk && next === charCodes.asterisk) {
       width++;
-      next = this.input.charCodeAt(this.state.pos + 2);
+      next = this.state.input.charCodeAt(this.state.pos + 2);
       type = tt.exponent;
     }
 
@@ -486,11 +472,13 @@ export default class Tokenizer extends LocationParser {
   }
 
   readToken_pipe_amp(code: number): void {
-    // '|&'
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    // '||' '&&' '||=' '&&='
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
 
     if (next === code) {
-      if (this.input.charCodeAt(this.state.pos + 2) === charCodes.equalsTo) {
+      if (
+        this.state.input.charCodeAt(this.state.pos + 2) === charCodes.equalsTo
+      ) {
         this.finishOp(tt.assign, 3);
       } else {
         this.finishOp(
@@ -506,10 +494,6 @@ export default class Tokenizer extends LocationParser {
       if (next === charCodes.greaterThan) {
         this.finishOp(tt.pipeline, 2);
         return;
-      } else if (next === charCodes.rightCurlyBrace && this.hasPlugin("flow")) {
-        // '|}'
-        this.finishOp(tt.braceBarR, 2);
-        return;
       }
     }
 
@@ -526,7 +510,7 @@ export default class Tokenizer extends LocationParser {
 
   readToken_caret(): void {
     // '^'
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
     if (next === charCodes.equalsTo) {
       this.finishOp(tt.assign, 2);
     } else {
@@ -536,14 +520,17 @@ export default class Tokenizer extends LocationParser {
 
   readToken_plus_min(code: number): void {
     // '+-'
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
 
     if (next === code) {
       if (
         next === charCodes.dash &&
         !this.inModule &&
-        this.input.charCodeAt(this.state.pos + 2) === charCodes.greaterThan &&
-        lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.pos))
+        this.state.input.charCodeAt(this.state.pos + 2) ===
+          charCodes.greaterThan &&
+        lineBreak.test(
+          this.state.input.slice(this.state.lastTokEnd, this.state.pos),
+        )
       ) {
         // A `-->` line comment
         this.skipLineComment(3);
@@ -564,16 +551,20 @@ export default class Tokenizer extends LocationParser {
 
   readToken_lt_gt(code: number): void {
     // '<>'
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
     let size = 1;
 
     if (next === code) {
       size =
         code === charCodes.greaterThan &&
-        this.input.charCodeAt(this.state.pos + 2) === charCodes.greaterThan
+        this.state.input.charCodeAt(this.state.pos + 2) ===
+          charCodes.greaterThan
           ? 3
           : 2;
-      if (this.input.charCodeAt(this.state.pos + size) === charCodes.equalsTo) {
+      if (
+        this.state.input.charCodeAt(this.state.pos + size) ===
+        charCodes.equalsTo
+      ) {
         this.finishOp(tt.assign, size + 1);
         return;
       }
@@ -585,8 +576,8 @@ export default class Tokenizer extends LocationParser {
       next === charCodes.exclamationMark &&
       code === charCodes.lessThan &&
       !this.inModule &&
-      this.input.charCodeAt(this.state.pos + 2) === charCodes.dash &&
-      this.input.charCodeAt(this.state.pos + 3) === charCodes.dash
+      this.state.input.charCodeAt(this.state.pos + 2) === charCodes.dash &&
+      this.state.input.charCodeAt(this.state.pos + 3) === charCodes.dash
     ) {
       // `<!--`, an XML-style comment that should be interpreted as a line comment
       this.skipLineComment(4);
@@ -605,11 +596,11 @@ export default class Tokenizer extends LocationParser {
 
   readToken_eq_excl(code: number): void {
     // '=!'
-    const next = this.input.charCodeAt(this.state.pos + 1);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
     if (next === charCodes.equalsTo) {
       this.finishOp(
         tt.equality,
-        this.input.charCodeAt(this.state.pos + 2) === charCodes.equalsTo
+        this.state.input.charCodeAt(this.state.pos + 2) === charCodes.equalsTo
           ? 3
           : 2,
       );
@@ -626,8 +617,8 @@ export default class Tokenizer extends LocationParser {
 
   readToken_question(): void {
     // '?'
-    const next = this.input.charCodeAt(this.state.pos + 1);
-    const next2 = this.input.charCodeAt(this.state.pos + 2);
+    const next = this.state.input.charCodeAt(this.state.pos + 1);
+    const next2 = this.state.input.charCodeAt(this.state.pos + 2);
     if (next === charCodes.questionMark && !this.state.inType) {
       if (next2 === charCodes.equalsTo) {
         // '??='
@@ -651,10 +642,6 @@ export default class Tokenizer extends LocationParser {
 
   getTokenFromCode(code: number): void {
     switch (code) {
-      case charCodes.numberSign:
-        this.readToken_numberSign();
-        return;
-
       // The interpretation of a dot depends on whether it is followed
       // by a digit or another two dots.
 
@@ -687,19 +674,10 @@ export default class Tokenizer extends LocationParser {
         ++this.state.pos;
         this.finishToken(tt.bracketR);
         return;
-
       case charCodes.leftCurlyBrace:
-        if (
-          this.hasPlugin("flow") &&
-          this.input.charCodeAt(this.state.pos + 1) === charCodes.verticalBar
-        ) {
-          this.finishOp(tt.braceBarL, 2);
-        } else {
-          ++this.state.pos;
-          this.finishToken(tt.braceL);
-        }
+        ++this.state.pos;
+        this.finishToken(tt.braceL);
         return;
-
       case charCodes.rightCurlyBrace:
         ++this.state.pos;
         this.finishToken(tt.braceR);
@@ -708,7 +686,7 @@ export default class Tokenizer extends LocationParser {
       case charCodes.colon:
         if (
           this.hasPlugin("functionBind") &&
-          this.input.charCodeAt(this.state.pos + 1) === charCodes.colon
+          this.state.input.charCodeAt(this.state.pos + 1) === charCodes.colon
         ) {
           this.finishOp(tt.doubleColon, 2);
         } else {
@@ -720,10 +698,6 @@ export default class Tokenizer extends LocationParser {
       case charCodes.questionMark:
         this.readToken_question();
         return;
-      case charCodes.atSign:
-        ++this.state.pos;
-        this.finishToken(tt.at);
-        return;
 
       case charCodes.graveAccent:
         ++this.state.pos;
@@ -731,7 +705,7 @@ export default class Tokenizer extends LocationParser {
         return;
 
       case charCodes.digit0: {
-        const next = this.input.charCodeAt(this.state.pos + 1);
+        const next = this.state.input.charCodeAt(this.state.pos + 1);
         // '0x', '0X' - hex number
         if (next === charCodes.lowercaseX || next === charCodes.uppercaseX) {
           this.readRadixNumber(16);
@@ -809,6 +783,25 @@ export default class Tokenizer extends LocationParser {
       case charCodes.tilde:
         this.finishOp(tt.tilde, 1);
         return;
+
+      case charCodes.atSign:
+        ++this.state.pos;
+        this.finishToken(tt.at);
+        return;
+
+      case charCodes.numberSign:
+        this.readToken_numberSign();
+        return;
+
+      case charCodes.backslash:
+        this.readWord();
+        return;
+
+      default:
+        if (isIdentifierStart(code)) {
+          this.readWord();
+          return;
+        }
     }
 
     this.raise(
@@ -818,7 +811,7 @@ export default class Tokenizer extends LocationParser {
   }
 
   finishOp(type: TokenType, size: number): void {
-    const str = this.input.slice(this.state.pos, this.state.pos + size);
+    const str = this.state.input.slice(this.state.pos, this.state.pos + size);
     this.state.pos += size;
     this.finishToken(type, str);
   }
@@ -827,10 +820,10 @@ export default class Tokenizer extends LocationParser {
     const start = this.state.pos;
     let escaped, inClass;
     for (;;) {
-      if (this.state.pos >= this.input.length) {
+      if (this.state.pos >= this.state.length) {
         this.raise(start, "Unterminated regular expression");
       }
-      const ch = this.input.charAt(this.state.pos);
+      const ch = this.state.input.charAt(this.state.pos);
       if (lineBreak.test(ch)) {
         this.raise(start, "Unterminated regular expression");
       }
@@ -848,16 +841,16 @@ export default class Tokenizer extends LocationParser {
       }
       ++this.state.pos;
     }
-    const content = this.input.slice(start, this.state.pos);
+    const content = this.state.input.slice(start, this.state.pos);
     ++this.state.pos;
 
     let mods = "";
 
-    while (this.state.pos < this.input.length) {
-      const char = this.input[this.state.pos];
-      const charCode = this.input.codePointAt(this.state.pos);
+    while (this.state.pos < this.state.length) {
+      const char = this.state.input[this.state.pos];
+      const charCode = this.state.input.codePointAt(this.state.pos);
 
-      if (VALID_REGEX_FLAGS.indexOf(char) > -1) {
+      if (VALID_REGEX_FLAGS.has(char)) {
         if (mods.indexOf(char) > -1) {
           this.raise(this.state.pos + 1, "Duplicate regular expression flag");
         }
@@ -902,12 +895,12 @@ export default class Tokenizer extends LocationParser {
     let total = 0;
 
     for (let i = 0, e = len == null ? Infinity : len; i < e; ++i) {
-      const code = this.input.charCodeAt(this.state.pos);
+      const code = this.state.input.charCodeAt(this.state.pos);
       let val;
 
       if (this.hasPlugin("numericSeparator")) {
-        const prev = this.input.charCodeAt(this.state.pos - 1);
-        const next = this.input.charCodeAt(this.state.pos + 1);
+        const prev = this.state.input.charCodeAt(this.state.pos - 1);
+        const next = this.state.input.charCodeAt(this.state.pos + 1);
         if (code === charCodes.underscore) {
           if (allowedSiblings.indexOf(next) === -1) {
             this.raise(this.state.pos, "Invalid or unexpected token");
@@ -961,18 +954,22 @@ export default class Tokenizer extends LocationParser {
     }
 
     if (this.hasPlugin("bigInt")) {
-      if (this.input.charCodeAt(this.state.pos) === charCodes.lowercaseN) {
+      if (
+        this.state.input.charCodeAt(this.state.pos) === charCodes.lowercaseN
+      ) {
         ++this.state.pos;
         isBigInt = true;
       }
     }
 
-    if (isIdentifierStart(this.input.codePointAt(this.state.pos))) {
+    if (isIdentifierStart(this.state.input.codePointAt(this.state.pos))) {
       this.raise(this.state.pos, "Identifier directly after number");
     }
 
     if (isBigInt) {
-      const str = this.input.slice(start, this.state.pos).replace(/[_n]/g, "");
+      const str = this.state.input
+        .slice(start, this.state.pos)
+        .replace(/[_n]/g, "");
       this.finishToken(tt.bigint, str);
       return;
     }
@@ -992,7 +989,7 @@ export default class Tokenizer extends LocationParser {
     }
     let octal =
       this.state.pos - start >= 2 &&
-      this.input.charCodeAt(start) === charCodes.digit0;
+      this.state.input.charCodeAt(start) === charCodes.digit0;
     if (octal) {
       if (this.state.strict) {
         this.raise(
@@ -1000,30 +997,30 @@ export default class Tokenizer extends LocationParser {
           "Legacy octal literals are not allowed in strict mode",
         );
       }
-      if (/[89]/.test(this.input.slice(start, this.state.pos))) {
+      if (/[89]/.test(this.state.input.slice(start, this.state.pos))) {
         octal = false;
       }
     }
 
-    let next = this.input.charCodeAt(this.state.pos);
+    let next = this.state.input.charCodeAt(this.state.pos);
     if (next === charCodes.dot && !octal) {
       ++this.state.pos;
       this.readInt(10);
       isFloat = true;
-      next = this.input.charCodeAt(this.state.pos);
+      next = this.state.input.charCodeAt(this.state.pos);
     }
 
     if (
       (next === charCodes.uppercaseE || next === charCodes.lowercaseE) &&
       !octal
     ) {
-      next = this.input.charCodeAt(++this.state.pos);
+      next = this.state.input.charCodeAt(++this.state.pos);
       if (next === charCodes.plusSign || next === charCodes.dash) {
         ++this.state.pos;
       }
       if (this.readInt(10) === null) this.raise(start, "Invalid number");
       isFloat = true;
-      next = this.input.charCodeAt(this.state.pos);
+      next = this.state.input.charCodeAt(this.state.pos);
     }
 
     if (this.hasPlugin("bigInt")) {
@@ -1035,12 +1032,14 @@ export default class Tokenizer extends LocationParser {
       }
     }
 
-    if (isIdentifierStart(this.input.codePointAt(this.state.pos))) {
+    if (isIdentifierStart(this.state.input.codePointAt(this.state.pos))) {
       this.raise(this.state.pos, "Identifier directly after number");
     }
 
     // remove "_" for numeric literal separator, and "n" for BigInts
-    const str = this.input.slice(start, this.state.pos).replace(/[_n]/g, "");
+    const str = this.state.input
+      .slice(start, this.state.pos)
+      .replace(/[_n]/g, "");
 
     if (isBigInt) {
       this.finishToken(tt.bigint, str);
@@ -1054,13 +1053,13 @@ export default class Tokenizer extends LocationParser {
   // Read a string value, interpreting backslash-escapes.
 
   readCodePoint(throwOnInvalid: boolean): number | null {
-    const ch = this.input.charCodeAt(this.state.pos);
+    const ch = this.state.input.charCodeAt(this.state.pos);
     let code;
 
     if (ch === charCodes.leftCurlyBrace) {
       const codePos = ++this.state.pos;
       code = this.readHexChar(
-        this.input.indexOf("}", this.state.pos) - this.state.pos,
+        this.state.input.indexOf("}", this.state.pos) - this.state.pos,
         throwOnInvalid,
       );
       ++this.state.pos;
@@ -1085,13 +1084,13 @@ export default class Tokenizer extends LocationParser {
     let out = "",
       chunkStart = ++this.state.pos;
     for (;;) {
-      if (this.state.pos >= this.input.length) {
+      if (this.state.pos >= this.state.length) {
         this.raise(this.state.start, "Unterminated string constant");
       }
-      const ch = this.input.charCodeAt(this.state.pos);
+      const ch = this.state.input.charCodeAt(this.state.pos);
       if (ch === quote) break;
       if (ch === charCodes.backslash) {
-        out += this.input.slice(chunkStart, this.state.pos);
+        out += this.state.input.slice(chunkStart, this.state.pos);
         // $FlowFixMe
         out += this.readEscapedChar(false);
         chunkStart = this.state.pos;
@@ -1107,7 +1106,7 @@ export default class Tokenizer extends LocationParser {
         ++this.state.pos;
       }
     }
-    out += this.input.slice(chunkStart, this.state.pos++);
+    out += this.state.input.slice(chunkStart, this.state.pos++);
     this.finishToken(tt.string, out);
   }
 
@@ -1118,14 +1117,14 @@ export default class Tokenizer extends LocationParser {
       chunkStart = this.state.pos,
       containsInvalid = false;
     for (;;) {
-      if (this.state.pos >= this.input.length) {
+      if (this.state.pos >= this.state.length) {
         this.raise(this.state.start, "Unterminated template");
       }
-      const ch = this.input.charCodeAt(this.state.pos);
+      const ch = this.state.input.charCodeAt(this.state.pos);
       if (
         ch === charCodes.graveAccent ||
         (ch === charCodes.dollarSign &&
-          this.input.charCodeAt(this.state.pos + 1) ===
+          this.state.input.charCodeAt(this.state.pos + 1) ===
             charCodes.leftCurlyBrace)
       ) {
         if (this.state.pos === this.state.start && this.match(tt.template)) {
@@ -1139,12 +1138,12 @@ export default class Tokenizer extends LocationParser {
             return;
           }
         }
-        out += this.input.slice(chunkStart, this.state.pos);
+        out += this.state.input.slice(chunkStart, this.state.pos);
         this.finishToken(tt.template, containsInvalid ? null : out);
         return;
       }
       if (ch === charCodes.backslash) {
-        out += this.input.slice(chunkStart, this.state.pos);
+        out += this.state.input.slice(chunkStart, this.state.pos);
         const escaped = this.readEscapedChar(true);
         if (escaped === null) {
           containsInvalid = true;
@@ -1153,11 +1152,13 @@ export default class Tokenizer extends LocationParser {
         }
         chunkStart = this.state.pos;
       } else if (isNewLine(ch)) {
-        out += this.input.slice(chunkStart, this.state.pos);
+        out += this.state.input.slice(chunkStart, this.state.pos);
         ++this.state.pos;
         switch (ch) {
           case charCodes.carriageReturn:
-            if (this.input.charCodeAt(this.state.pos) === charCodes.lineFeed) {
+            if (
+              this.state.input.charCodeAt(this.state.pos) === charCodes.lineFeed
+            ) {
               ++this.state.pos;
             }
           case charCodes.lineFeed:
@@ -1180,7 +1181,7 @@ export default class Tokenizer extends LocationParser {
 
   readEscapedChar(inTemplate: boolean): string | null {
     const throwOnInvalid = !inTemplate;
-    const ch = this.input.charCodeAt(++this.state.pos);
+    const ch = this.state.input.charCodeAt(++this.state.pos);
     ++this.state.pos;
     switch (ch) {
       case charCodes.lowercaseN:
@@ -1204,18 +1205,22 @@ export default class Tokenizer extends LocationParser {
       case charCodes.lowercaseF:
         return "\f";
       case charCodes.carriageReturn:
-        if (this.input.charCodeAt(this.state.pos) === charCodes.lineFeed) {
+        if (
+          this.state.input.charCodeAt(this.state.pos) === charCodes.lineFeed
+        ) {
           ++this.state.pos;
         }
       case charCodes.lineFeed:
         this.state.lineStart = this.state.pos;
         ++this.state.curLine;
+      case charCodes.lineSeparator:
+      case charCodes.paragraphSeparator:
         return "";
       default:
         if (ch >= charCodes.digit0 && ch <= charCodes.digit7) {
           const codePos = this.state.pos - 1;
           // $FlowFixMe
-          let octalStr = this.input
+          let octalStr = this.state.input
             .substr(this.state.pos - 1, 3)
             .match(/^[0-7]+/)[0];
           let octal = parseInt(octalStr, 8);
@@ -1239,6 +1244,7 @@ export default class Tokenizer extends LocationParser {
           this.state.pos += octalStr.length - 1;
           return String.fromCharCode(octal);
         }
+
         return String.fromCharCode(ch);
     }
   }
@@ -1266,23 +1272,28 @@ export default class Tokenizer extends LocationParser {
   // as a micro-optimization.
 
   readWord1(): string {
+    let word = "";
     this.state.containsEsc = false;
-    let word = "",
-      first = true,
-      chunkStart = this.state.pos;
-    while (this.state.pos < this.input.length) {
-      const ch = this.input.codePointAt(this.state.pos);
+    const start = this.state.pos;
+    let chunkStart = this.state.pos;
+
+    while (this.state.pos < this.state.length) {
+      const ch = this.state.input.codePointAt(this.state.pos);
       if (isIdentifierChar(ch)) {
         this.state.pos += ch <= 0xffff ? 1 : 2;
       } else if (this.state.isIterator && ch === charCodes.atSign) {
-        this.state.pos += 1;
+        ++this.state.pos;
       } else if (ch === charCodes.backslash) {
         this.state.containsEsc = true;
 
-        word += this.input.slice(chunkStart, this.state.pos);
+        word += this.state.input.slice(chunkStart, this.state.pos);
         const escStart = this.state.pos;
+        const identifierCheck =
+          this.state.pos === start ? isIdentifierStart : isIdentifierChar;
 
-        if (this.input.charCodeAt(++this.state.pos) !== charCodes.lowercaseU) {
+        if (
+          this.state.input.charCodeAt(++this.state.pos) !== charCodes.lowercaseU
+        ) {
           this.raise(
             this.state.pos,
             "Expecting Unicode escape sequence \\uXXXX",
@@ -1291,8 +1302,11 @@ export default class Tokenizer extends LocationParser {
 
         ++this.state.pos;
         const esc = this.readCodePoint(true);
-        // $FlowFixMe (thinks esc may be null, but throwOnInvalid is true)
-        if (!(first ? isIdentifierStart : isIdentifierChar)(esc, true)) {
+
+        if (
+          // $FlowFixMe (thinks esc may be null, but throwOnInvalid is true)
+          !identifierCheck(esc, true)
+        ) {
           this.raise(escStart, "Invalid Unicode escape");
         }
 
@@ -1302,9 +1316,8 @@ export default class Tokenizer extends LocationParser {
       } else {
         break;
       }
-      first = false;
     }
-    return word + this.input.slice(chunkStart, this.state.pos);
+    return word + this.state.input.slice(chunkStart, this.state.pos);
   }
 
   isIterator(word: string): boolean {
@@ -1316,14 +1329,10 @@ export default class Tokenizer extends LocationParser {
 
   readWord(): void {
     const word = this.readWord1();
-    let type = tt.name;
+    const type = keywordTypes[word] || tt.name;
 
-    if (this.isKeyword(word)) {
-      if (this.state.containsEsc) {
-        this.raise(this.state.pos, `Escape sequence in keyword ${word}`);
-      }
-
-      type = keywordTypes[word];
+    if (type.keyword && this.state.containsEsc) {
+      this.raise(this.state.pos, `Escape sequence in keyword ${word}`);
     }
 
     // Allow @@iterator and @@asyncIterator as a identifier only inside type
@@ -1354,11 +1363,10 @@ export default class Tokenizer extends LocationParser {
     // `tt.name`.
     if (
       prevType === tt._return ||
-      prevType === tt._yield ||
       (prevType === tt.name && this.state.exprAllowed)
     ) {
       return lineBreak.test(
-        this.input.slice(this.state.lastTokEnd, this.state.start),
+        this.state.input.slice(this.state.lastTokEnd, this.state.start),
       );
     }
 
@@ -1378,8 +1386,8 @@ export default class Tokenizer extends LocationParser {
 
     if (
       prevType === tt._var ||
-      prevType === tt._let ||
-      prevType === tt._const
+      prevType === tt._const ||
+      prevType === tt.name
     ) {
       return false;
     }